Irish clans are traditional
kinship
In anthropology, kinship is the web of social relationships that form an important part of the lives of all humans in all societies, although its exact meanings even within this discipline are often debated. Anthropologist Robin Fox says that ...
groups sharing a common surname and heritage and existing in a lineage-based society, originating prior to the 17th century. A clan (or in Irish, plural ) included the chief and his
patrilineal relatives; however, Irish clans also included unrelated clients of the chief. These unrelated clients and their agnatic descendants were ineligible to be elected chief, but nonetheless assumed the name of the leading lineage as a show of allegiance.
Beginning in the 8th century, various genealogical collections were compiled purporting to trace the ancestry of these clans. Among them are genealogies in
Rawlinson B 502, the
Book of Ballymote
The ''Book of Ballymote'' (, RIA MS 23 P 12, 275 foll.), was written in 1390 or 1391 in or near the town of Ballymote, now in County Sligo, but then in the tuath of Corann.
According to David Sellar who was the Lord Lyon King of Arms in ...
, the
Book of Lecan, the
''Leabhar MĂłr na nGenealach'' compiled by Dubhaltach MacFhirbisigh, and the
à Cléirigh Book of Genealogies. In all of these cases, the genealogies listed state the agnatic descent of the chiefs and chieftains, and not necessarily every member of the clan. At least one genetic study has concluded that while these genealogies appear fairly accurate back to the Middle Ages, they are unreliable before the 7th century.
Definition of "clan"
The Irish word ''clann'' is a borrowing from the Latin ''planta'', meaning 'a plant, an offshoot, offspring, a single child or children, by extension race or descendants'. For instance, the
O'Daly family were poetically known as ''Clann Dalaigh'', from a remote ancestor called Dalach.
''Clann'' was used in the later Middle Ages to provide a plural for surnames beginning with ''Mac'' meaning 'son of'. For example, "Clann CĂĄrthaigh" meant the men of the MacCarthy family and "
Clann Suibhne" meant the men of the MacSweeny family. ''Clann'' was also used to denote a subgroup within a wider surname, the descendants of a recent common ancestor, such as the ''Clann Aodha Buidhe'' or the ''
O'Neills'' of Clandeboy, whose ancestor was Aodh Buidhe who died in 1298. Such a "clan", if sufficiently closely related, could have common interests in landownership, but any political power wielded by their chief was territorially based.
From ancient times, Irish society was organised around traditional kinship groups or clans. These clans traced their origins to larger pre-surname population groupings or clans such as
UĂ BriĂșin
The UĂ BriĂșin were a royal dynasty of Connacht. Their eponymous apical ancestor was BriĂłn, son of Eochaid Mugmedon and Mongfind, and an elder half brother of Niall of the Nine Hostages. They formed part of the Connachta, along with th ...
in
Connacht
Connacht or Connaught ( ; or ), is the smallest of the four provinces of Ireland, situated in the west of Ireland. Until the ninth century it consisted of several independent major Gaelic kingdoms (UĂ Fiachrach, UĂ BriĂșin, UĂ Maine, C ...
,
EĂłganachta
The EĂłganachta (Modern , ) were an Irish dynasty centred on Rock of Cashel, Cashel which dominated southern Ireland (namely the Kingdom of Munster) from the 6/7th to the 10th centuries, and following that, in a restricted form, the Kingdom of De ...
and
DĂĄl gCais
The Dalcassians ( ) are a Gaels, Gaelic Irish clan, generally accepted by contemporary scholarship as being a branch of the Déisi Muman, that became very powerful in Ireland during the 10th century. Their genealogies claimed descent from Tål ...
in
Munster
Munster ( or ) is the largest of the four provinces of Ireland, located in the south west of the island. In early Ireland, the Kingdom of Munster was one of the kingdoms of Gaelic Ireland ruled by a "king of over-kings" (). Following the Nor ...
,
Uà Néill
The UĂ NĂ©ill (; meaning "descendants of Niall") are Irish dynasties that claim descent from Niall NoĂgĂallach (Niall of the Nine Hostages), a historical King of Tara who is believed to have died around c. 405. They are generally divided ...
in
Ulster
Ulster (; or ; or ''Ulster'') is one of the four traditional or historic provinces of Ireland, Irish provinces. It is made up of nine Counties of Ireland, counties: six of these constitute Northern Ireland (a part of the United Kingdom); t ...
, and
Fir Domnann
The Fir Domnann were a people named in Irish legendary history.
The name ''Fir Domnann'' is based on the root ''dumno''-, which means both 'deep' and 'the world'. The suffix -''on''- often occurs in Gaulish and British divine names. The tribal n ...
in
Leinster
Leinster ( ; or ) is one of the four provinces of Ireland, in the southeast of Ireland.
The modern province comprises the ancient Kingdoms of Meath, Leinster and Osraige, which existed during Gaelic Ireland. Following the 12th-century ...
. Within these larger groupings there tended to be one ''
sept'' (division) who through war and politics became more powerful than others for a period of time and the leaders of some were accorded the status of
royalty
Royalty may refer to:
* the mystique/prestige bestowed upon monarchs
** one or more monarchs, such as kings, queens, emperors, empresses, princes, princesses, etc.
*** royal family, the immediate family of a king or queen-regnant, and sometimes h ...
in Gaelic Ireland. Some of the more important septs to achieve this power were
O'Connor in Connacht,
MacCarthy of Desmond and
O'Brien of Thomond in Munster, Ă Neill of Clandeboy in Ulster, and
MacMorrough Kavanagh in Leinster.
The largely symbolic role of
High king of Ireland
High King of Ireland ( ) was a royal title in Gaelic Ireland held by those who had, or who are claimed to have had, lordship over all of Ireland. The title was held by historical kings and was later sometimes assigned anachronously or to leg ...
tended to rotate among the leaders of these royal clans. The larger or more important clans were led by a or chief who had the status of royalty and the smaller and more dependent clans were led by chieftains. Under
Brehon law
Early Irish law, also called Brehon law (from the old Irish word breithim meaning judge), comprised the statutes which governed everyday life in Early Medieval Ireland. They were partially eclipsed by the Norman invasion of 1169, but underwe ...
, the leaders of Irish clans were appointed by their kinsmen as custodians of the clan and were responsible for maintaining and protecting their clan and its property. The clan system formed the basis of society up to the 17th century.
Origins
The O'Rahilly doctrine
According to
T. F. O'Rahilly, in his works ''Goides and Their Predecessors'' and later ''Early Irish History'', there were a total of four waves of Celtic invasions of the British Isles and that the first three of these were pre-Gaelic.
[Brady, Ciaran; O'Dowd, Mary; Walter, Brian (1989). pp. 22 and 26][Dillon, Myles; Chadwick, Nora (2000). p. 5] According to O'Rahilly, these were people who had largely remained unconquered by the
Romans whose territory was mostly restricted to the broad plains of
England
England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...
. A larger part of England remained out of the control of the West Germanic people who invaded after the imperial collapse of
Roman Britain
Roman Britain was the territory that became the Roman province of ''Britannia'' after the Roman conquest of Britain, consisting of a large part of the island of Great Britain. The occupation lasted from AD 43 to AD 410.
Julius Caes ...
and who founded the English nation.
O'Rahilly's version of the origins of the Irish, as supported by C. Thomas Cairney and John Grenham is as follows: The first of the Celtic invaders of Ireland were known as the
Cruthin
The Cruthin (; or ; ) were a people of early medieval Ireland. Their heartland was in Ulster and included parts of the present-day counties of Antrim, Down and Londonderry. They are also said to have lived in parts of Leinster and Connacht ...
who arrived between 800 and 500
BC.
The second wave of Celts to come to Ireland were known as the
Erainn and this is supposedly where the Gaelic name for Ireland,
Erin, originated from. These people arrived between 500 and 100 BC. They came from the area which is today known as
Belgium
Belgium, officially the Kingdom of Belgium, is a country in Northwestern Europe. Situated in a coastal lowland region known as the Low Countries, it is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeas ...
and had superior iron weaponry, and thus eventually reduced the Irish Cruthin to tributary status. The third wave of Celtic settlement in Ireland came from
Continental Europe
Continental Europe or mainland Europe is the contiguous mainland of Europe, excluding its surrounding islands. It can also be referred to ambiguously as the European continent, â which can conversely mean the whole of Europe â and, by som ...
during the first century BC and this was probably because of pressure from the Romans on the south of
Gaul
Gaul () was a region of Western Europe first clearly described by the Roman people, Romans, encompassing present-day France, Belgium, Luxembourg, and parts of Switzerland, the Netherlands, Germany, and Northern Italy. It covered an area of . Ac ...
. These people were known as the
Dumnonii
The Dumnonii or Dumnones were a Britons (historical), British List of ancient Celtic peoples and tribes, tribe who inhabited Dumnonia, the area now known as Cornwall and Devon (and some areas of present-day Dorset and Somerset) in the further pa ...
and gave their name to
Devon
Devon ( ; historically also known as Devonshire , ) is a ceremonial county in South West England. It is bordered by the Bristol Channel to the north, Somerset and Dorset to the east, the English Channel to the south, and Cornwall to the west ...
in England. Their most powerful branch in Ireland was the
Laigin
The Laigin, modern spelling Laighin (), were a Gaelic population group of early Ireland. They gave their name to the Kingdom of Leinster, which in the medieval era was known in Irish as ''CĂłiced Laigen'', meaning "Fifth/province of the Leinste ...
who gave their name to
Leinster
Leinster ( ; or ) is one of the four provinces of Ireland, in the southeast of Ireland.
The modern province comprises the ancient Kingdoms of Meath, Leinster and Osraige, which existed during Gaelic Ireland. Following the 12th-century ...
. A branch of the Irish group of the Dumnonii settled just to the south of
Dumbarton
Dumbarton (; , or ; or , meaning 'fort of the Britons (historical), Britons') is a town in West Dunbartonshire, Scotland, on the north bank of the River Clyde where the River Leven, Dunbartonshire, River Leven flows into the Clyde estuary. ...
in
Scotland
Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...
and were the ancestors of the
Strathclyde-Britons.
The fourth and last major Celtic settlements in Ireland took place around 50 BC. This was directly because of Roman attempts to dominate the
Gauls
The Gauls (; , ''GalĂĄtai'') were a group of Celts, Celtic peoples of mainland Europe in the Iron Age Europe, Iron Age and the Roman Gaul, Roman period (roughly 5th century BC to 5th century AD). Their homeland was known as Gaul (''Gallia''). Th ...
of Continental Europe. This included, among others, a group known as the ''Feni'' who came to Ireland directly from the Continent and according to tradition landed in south
Kerry and the
Boyne estuary. The earlier inhabitants of the country fiercely resisted the newcomers who were referred to as the ''
Gaeil'' because they spoke the
Gaelic language
The Goidelic ( ) or Gaelic languages (; ; ) form one of the two groups of Insular Celtic languages, the other being the Brittonic languages.
Goidelic languages historically formed a dialect continuum stretching from Ireland through the Isle o ...
. The power and influence of the ''Gaeils'' gradually spread over the next three centuries, northwards, from Kerry into
Tipperary and
Limerick
Limerick ( ; ) is a city in western Ireland, in County Limerick. It is in the Provinces of Ireland, province of Munster and is in the Mid-West Region, Ireland, Mid-West which comprises part of the Southern Region, Ireland, Southern Region. W ...
, as well as to the west into
Galway
Galway ( ; , ) is a City status in Ireland, city in (and the county town of) County Galway. It lies on the River Corrib between Lough Corrib and Galway Bay. It is the most populous settlement in the province of Connacht, the List of settleme ...
and
Roscommon
Roscommon (; ; ) is the county town and the largest town in County Roscommon in Republic of Ireland, Ireland. It is roughly in the centre of Ireland, near the meeting of the N60 road (Ireland), N60, N61 road (Ireland), N61 and N63 road (Irelan ...
. By the 5th century they were dominant in most of Ireland and had established dynasties and tribal groups. These groups determined the Irish politics and culture until the
Norman invasion of Ireland
The Anglo-Norman invasion of Ireland took place during the late 12th century, when Anglo-Normans gradually conquered and acquired large swathes of land in Ireland over which the monarchs of England then claimed sovereignty. The Anglo-Normans ...
which took place during the late 12th century.
[Grenham, John (1993). pp. 18-19]
Modern opinion

O'Rahilly's version of history has been questioned by archaeologists and historians who have played down the role of the Cruthin as invaders, including by
Ian Adamson.
[Brady, Ciaran; O'Dowd, Mary; Walter, Brian (1989). pp. 22 and 26. Quoting: Adamson, Ian (1974). ''Cruthin: The Ancient Kindred''. Newtownards. p. 12] O'Rahilly's history has been entirely unaccepted by some historians including
Francis John Byrne
Francis John Byrne (1934 â 30 December 2017) was an Irish historian.
Born in Shanghai where his father, a Dundalk man, captained a ship on the Yellow River, Byrne was evacuated with his mother to Australia on the outbreak of World War II. A ...
.
[Brady, Ciaran; O'Dowd, Mary; Walter, Brian (1989). p. 22. Quoting: Byrne. F. J. (1965). ''The Ireland of Saint Columba''. Historical Studies, 5, p. 38] According to
Myles Dillon and
Nora K. Chadwick, while O'Rahilly's version of history has been accepted by some scholars and dismissed by others, it is an entirely traditional history that he had sourced from ''
Lebor GabĂĄla Ărenn
''Lebor GabĂĄla Ărenn'' (literally "The Book of Ireland's Taking"; Modern Irish spelling: ''Leabhar GabhĂĄla Ăireann'', known in English as ''The Book of Invasions'') is a collection of poems and prose narratives in the Irish language inten ...
'' which was a historic manuscript written in the 11th century, also known as the ''Book of the Invasions of Ireland'', and not historic facts based on contemporary evidence.
[Dillon, Myles; Chadwick, Nora (2000). pp. 5-6] J. P. Mallory stated that O'Rahilly has argued that this manuscript showed that the
medieval
In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of World history (field), global history. It began with the fall of the West ...
people of Ireland had seen a series of invasions from whom various dynasties and families might have traced their origins to.
According to Mallory, Ireland may have been inhabited by
Paleolithic
The Paleolithic or Palaeolithic ( years ago) ( ), also called the Old Stone Age (), is a period in human prehistory that is distinguished by the original development of stone tools, and which represents almost the entire period of human prehist ...
(Old Stone Age) hunters, but that the evidence for this is only a few pieces of
flint
Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, categorized as the variety of chert that occurs in chalk or marly limestone. Historically, flint was widely used to make stone tools and start ...
. The first actual evidence of human residence in Ireland dates to around 8000 BC. Evidence of the first
Neolithic
The Neolithic or New Stone Age (from Ancient Greek, Greek 'new' and 'stone') is an archaeological period, the final division of the Stone Age in Mesopotamia, Asia, Europe and Africa (c. 10,000 BCE to c. 2,000 BCE). It saw the Neolithic Revo ...
farmers in Ireland dates to around 4000 BC. There is little evidence of a warrior elite in Ireland before 1500 BC and evidence for this appears during the
Bronze Age
The Bronze Age () was a historical period characterised principally by the use of bronze tools and the development of complex urban societies, as well as the adoption of writing in some areas. The Bronze Age is the middle principal period of ...
where everyone of a wealthy class had weaponry. The Irish language first appeared from between 700/600 BC and 400
AD during the
Iron Age
The Iron Age () is the final epoch of the three historical Metal Ages, after the Chalcolithic and Bronze Age. It has also been considered as the final age of the three-age division starting with prehistory (before recorded history) and progre ...
. During this time, the Irish people came into contact with Roman traders.
According to the writers of ''Ulster: An Illustrated History'', there is evidence for the
Ulaid
(Old Irish, ) or (Irish language, Modern Irish, ) was a Gaelic Ireland, Gaelic Provinces of Ireland, over-kingdom in north-eastern Ireland during the Middle Ages made up of a confederation of dynastic groups. Alternative names include , which ...
who are referred to as the
Erainn by some genealogists which is also the name given on
Ptolemy's map of Ireland which dates from the second century AD for the
Iverni
The Iverni (, ') were a people of early Ireland first mentioned in Ptolemy's 2nd century ''Geography'' as living in the extreme south-west of the island. He also locates a "city" called Ivernis (, ') in their territory, and observes that this se ...
who lived in
County Cork
County Cork () is the largest and the southernmost Counties of Ireland, county of Republic of Ireland, Ireland, named after the city of Cork (city), Cork, the state's second-largest city. It is in the Provinces of Ireland, province of Munster ...
, as well as being the origin of the name for Ireland. The centre of the Ulaid's land was in the
Diocese of Down. The main population group of the Ulaid was the Cruthin whose territory was in the
Diocese of Connor and Dromore. There is also evidence for the
LoĂgis
LoĂgis () is the name of an Irish tribe, as it is called by contemporary scholars. Formerly, scholars generally called the tribe ''Laoighis'' or ''Laeighis'' in Irish, ''Lagisia'' in Latin, and ''Leix'' in English. LoĂgis is also the name of the ...
in Leinster and the
CĂarraige in
Munster
Munster ( or ) is the largest of the four provinces of Ireland, located in the south west of the island. In early Ireland, the Kingdom of Munster was one of the kingdoms of Gaelic Ireland ruled by a "king of over-kings" (). Following the Nor ...
who also belong to this group and it is possible that their ancestors in Ireland were pre-Celtic.
[Brady, Ciaran; O'Dowd, Mary; Walter, Brian (1989). p. 27] It is also possible to identify from Ptolemy's map the
DĂĄl Riata
DĂĄl Riata or DĂĄl Riada (also Dalriada) () was a Gaels, Gaelic Monarchy, kingdom that encompassed the Inner Hebrides, western seaboard of Scotland and north-eastern Ireland, on each side of the North Channel (Great Britain and Ireland), North ...
of
County Antrim
County Antrim (named after the town of Antrim, County Antrim, Antrim, ) is one of the six counties of Northern Ireland, located within the historic Provinces of Ireland, province of Ulster. Adjoined to the north-east shore of Lough Neagh, the c ...
who later founded a powerful kingdom in
Argyll
Argyll (; archaically Argyle; , ), sometimes called Argyllshire, is a Shires of Scotland, historic county and registration county of western Scotland. The county ceased to be used for local government purposes in 1975 and most of the area ...
, Scotland. The 11th century ''Lebor GabĂĄla Ărenn'' or ''Book of the Invasions of Ireland'', describes a series of failed invasions of Ireland before settlement in the 8th century. However, by the 8th century battles in Ireland were not between the natives and invaders but between tribes and dynasties for control of different parts of the island.
Donnchadh Ă CorrĂĄin
Donnchadh Ă CorrĂĄin (28 February 1942 â 25 October 2017) was an Republic of Ireland, Irish historian and professor emeritus of medieval history at University College Cork. He earned his BA in history and Irish from UCC, graduating in 1964.
...
put the evidence for the Irish naitional identity back to the 7th century emphasising the impact that
Christianity
Christianity is an Abrahamic monotheistic religion, which states that Jesus in Christianity, Jesus is the Son of God (Christianity), Son of God and Resurrection of Jesus, rose from the dead after his Crucifixion of Jesus, crucifixion, whose ...
had on the people there.
In 1002, the
Uà Néill
The UĂ NĂ©ill (; meaning "descendants of Niall") are Irish dynasties that claim descent from Niall NoĂgĂallach (Niall of the Nine Hostages), a historical King of Tara who is believed to have died around c. 405. They are generally divided ...
lost the high kingship of Ireland to the leader of the
Dal gCais or
Dalcassians, Brian Boru. It was during the century of declining Uà Néill dominance that surnames first started being used in Ireland. This meant that Ireland was one of the first countries in Europe to start using surnames. Descendants of
Niall of the Nine Hostages
Niall NoĂgĂallach (; Old Irish "having nine hostages"), or Niall of the Nine Hostages, was a legendary, semi-historical Irish king who was the ancestor of the UĂ NĂ©ill dynasties that dominated Ireland from the 6th to the 10th centuries. ...
, who was the ancestor of the Uà Néill dynasty, include people with the surnames
O'Boyle,
O'Connor and
O'Donnell
The O'Donnell dynasty ( or ''Ă Domhnaill,'' ''Ă Doáčnaill'' ''or Ua Domaill;'' meaning "descendant of DĂłnal") were the dominant Irish clan of the kingdom of Tyrconnell in Ulster in the north of medieval and early modern Ireland.
Naming ...
. From the Dal gCais or Dalcassians came the surnames
O'Brien and
Kennedy.
Social structure

Within the ''Gaeil'' there was distinction between the tribes of the south from those of the north, and also from those of the west. The tribes in the south called themselves the
Eoghanacht and in about the year 400 AD they established at
Cashel
Cashel (an Anglicised form of the Irish language word ''Caiseal'', meaning "stone fort") may refer to:
Places in Ireland
*Cashel, County Tipperary
**The Rock of Cashel, an ancient, hilltop fortress complex for which Cashel is named
** Archbishop ...
a dynasty which held power throughout most of southern Ireland from the 5th to 12th centuries. The Munster families of
O'Sullivan O'Sullivan may refer to:
People
* O'Sullivan family, a gaelic Irish clan
* O'Sullivan (surname), a family name
* Sullivan (surname), a variation of the O'Sullivan family name
Places
* O'Sullivan Dam, Washington, United States
* O'Sullivan Army He ...
,
MacCarthy and
O'Connell O'Connell may refer to:
People
*O'Connell (name), people with O'Connell as a last name or given name
Schools
* Bishop Denis J. O'Connell High School, a high school in Arlington, Virginia
Places
* Mount O'Connell National Park in Queensland ...
claim descent from the Eoghanacht.
In the midlands of Ireland, the ''Gaeil'' tribes were known as
Connachta
The Connachta are a group of medieval Irish dynasty, dynasties who claimed descent from the legendary High King of Ireland, High King Conn of the Hundred Battles, Conn Cétchathach (Conn of the Hundred Battles). The modern western Provinces of ...
and their name continues in the modern province of
Connacht
Connacht or Connaught ( ; or ), is the smallest of the four provinces of Ireland, situated in the west of Ireland. Until the ninth century it consisted of several independent major Gaelic kingdoms (UĂ Fiachrach, UĂ BriĂșin, UĂ Maine, C ...
. The most important of the Connacta tribes was the Uà Néill who claimed descent from Niall of the Nine Hostages. Niall's brothers included
Ailill,
Brion and
Fiachra who were founders of the important Connachta tribes of Ui Ailella,
UĂ BriĂșin
The UĂ BriĂșin were a royal dynasty of Connacht. Their eponymous apical ancestor was BriĂłn, son of Eochaid Mugmedon and Mongfind, and an elder half brother of Niall of the Nine Hostages. They formed part of the Connachta, along with th ...
and
UĂ Fiachrach.
Although the Eoghanacht and Uà Néill were the most powerful tribal groups in Ireland, there were others who were locally powerful including the
AirgĂalla in the north-east where they controlled what is now the counties of
Tyrone,
Armagh
Armagh ( ; , , " Macha's height") is a city and the county town of County Armagh, in Northern Ireland, as well as a civil parish. It is the ecclesiastical capital of Ireland â the seat of the Archbishops of Armagh, the Primates of All ...
,
Fermanagh and
Monaghan
Monaghan ( ; ) is the county town of County Monaghan, Republic of Ireland, Ireland. It also provides the name of its Civil parishes in Ireland, civil parish and Monaghan (barony), Monaghan barony.
The population of the town as of the 2022 cen ...
. There was also the
Ulaid
(Old Irish, ) or (Irish language, Modern Irish, ) was a Gaelic Ireland, Gaelic Provinces of Ireland, over-kingdom in north-eastern Ireland during the Middle Ages made up of a confederation of dynastic groups. Alternative names include , which ...
h who inhabited what is now the counties of
Down and
Antrim.
Within these large areas there were up to 150 small divisions known as
tĂșatha and the names of many of these are reflected today in the names of the
Irish baronies that make up the modern counties. Each tĂșath had a ruler or
petty king who owed allegiance to a more powerful king who was over-king of three or more tĂșatha. This over-king would in turn be subordinate to the king of a province, usually either the Eoghanacht or UĂ NĂ©ill.
The succession of kings or chiefs was governed by a system known as
Tanistry whereby after a chief had died, the new chief would be elected from all agnatic cousins descended from a patrilineal grandfather or great-grandfather.
However, according to
Eoin MacNeill
Eoin MacNeill (; born John McNeill; 15 May 1867 â 15 October 1945) was an Irish scholar, Irish language enthusiast, Gaelic revivalist, nationalist, and politician who served as Minister for Education from 1922 to 1925, Ceann Comhairle of D ...
, the system known as tanistry which also took place before the position of king or chief had become vacant is not found in records until the time of
feudalism
Feudalism, also known as the feudal system, was a combination of legal, economic, military, cultural, and political customs that flourished in Middle Ages, medieval Europe from the 9th to 15th centuries. Broadly defined, it was a way of struc ...
in Ireland which was not until the time of the Normans, and it was preceded by the similar system known as ''Rigdomna'' but which took place only after the position of king or chief had become vacant.
This theory however, was disputed by
GearĂłid Mac Niocaill who stated that there is no good evidence to support that the usage of the term ''Rigdomna'' in early medieval Ireland was any different to that of ''tanaise'' (Tanistry) in late medieval Ireland and that the two terms were synonymous with each other. Although Mac Niocaill did state that MacNeill was correct in identifying a number of cases where ''Rigdomna'' was limited to a four generation group in early medieval Ireland but in late medieval Ireland it was almost always the son, brother or nephew of the king.
Tribes of the Cruthin
As per O'Rahilly's doctrine, the
Cruthin
The Cruthin (; or ; ) were a people of early medieval Ireland. Their heartland was in Ulster and included parts of the present-day counties of Antrim, Down and Londonderry. They are also said to have lived in parts of Leinster and Connacht ...
were the first Celts to settle in Ireland between about 800 and 500 BC. In line with this, according to Cairney, from them descended the following Irish tribes. Although it is not possible to prove O'Rahilly's history of the four Celtic invasions of Ireland or that the Cruthin were the first of these invasions, or that the following Irish tribes descended from them, according to historian Sean Duffy, the existence of all three of the following Irish tribes in around the 7th century is supported by the literature of the time that came to Ireland with Christianity.
[Duffy (2011). pp. 14, 15, 18, 19: "This material, the most comprehensive to survive in any country of Dark Age Europe, enables us to reconstruct the political map of Ireland even at this early period".]
*The
Dal nAraide. Irish surnames that came from this tribe include:
O'Lynch, MacGenises, and
MacCartan. The latter two later became tributaries of the O'Neills.
*The
Soghain. Their chief was in later times known as
O'Mannin or Mannions and this has sometimes become Manning.
*The
LoĂgis
LoĂgis () is the name of an Irish tribe, as it is called by contemporary scholars. Formerly, scholars generally called the tribe ''Laoighis'' or ''Laeighis'' in Irish, ''Lagisia'' in Latin, and ''Leix'' in English. LoĂgis is also the name of the ...
. Irish surnames which came from this tribe include:
O'Mores,
O'Nolans, O'Dorans,
O'Lawlors and
O'Dowlings.
Tribes of the Erainn
As per O'Rahilly's doctrine, the
Erainn were the second wave of Celts to settle in Ireland between about 500 and 100 BC. In line with this, according to Cairney, from them descended the following Irish tribes. Although it is not possible to prove O'Rahilly's history of the four Celtic invasions of Ireland or that the Erainn were the second of these invasions, or that the following Irish tribes descended from them, according to historian Sean Duffy, with the exception of the Clann Choinleagain, the existence of all of the following Irish tribes in around the 7th century is supported by the literature of the time that came to Ireland with Christianity.
*The Clann Choinleagain (or MacGifoyles). This was an ancient clan located in the territory of the
O'Carrols of Ely.
*The
Conmaicne Rein. The chiefly families of this tribe were the MacRannalls,
O'Cornyns,
O'Farrells, O'Moledys and
O'Quins.
*The
Corca Dhuibhne. The chiefly families of this tribe were the
O'Connells and
O'Shea
O'Shea is a surname and, less often, a given name. It is an anglicized form of the Irish patronymic name à Séaghdha or à Sé, originating in the Kingdom of Corcu Duibne in County Kerry. Historian C. Thomas Cairney states that the O'Sheas were ...
s.
*The
Corca Laoghdne. The chiefly families of this tribe were the
O'Coffey,
O'Dinneen,
O'Driscoll,
O'Flynn,
O'Hea,
O'Hennessy and
O'Leary.
*The
Corco Modhruadh. The chiefly families of this tribe were the
O'Connors of
Corcomroe, MacCurtins, O'Loghlens or
O'Loughlins,
O'Davorens and the Corca Thine.
*The Dal Cairbre Arad. The chiefly family of this tribe was the
O'Dwyers.
*The
Dal gCais (
Dalcassians). The chiefly families of this tribe were the
O'Brien dynasty
The O'Brien dynasty (; ; genitive ''UĂ Bhriain'' ) was an Irish Clan and noble house of Munster, founded in the 10th century by Brian Boru of the DĂĄl gCais (Dalcassians). After becoming King of Munster, through conquest he established hims ...
who were the main chiefs, but also the
MacConsidines, MacDonnells, MacLysaghts,
MacMahons,
O'Ahernes,
O'Kennedys,
O'Shanahans, O'Duracks,
MacGraths,
O'Fogartys,
O'Galvins,
O'Gradys,
O'Hanrahans,
O'Hickeys,
O'Mearas,
O'Molonys, O'Moroneys, O'Hartagans, O'Lonergans,
Creaghs, O'Quins,
MacNamaras,
MacInerneys,
O'Deas and
O'Griffeys.
*The
Déisi
The ''Déisi'' were a social class in Ireland between the ancient and early medieval period. The various peoples listed under the heading ''déis'' shared a similar status in Gaelic Ireland, and had little or no actual kinship, though they were ...
. Their chief was
O'Phelan.
*The
Partraige. Their chiefly family was the
O'Malleys.
*The
Uaithni. Their chiefly family was the
O'Heffermans.
*The
UĂ Bairrche. Their chiefly families were the
O'Tracys and
MacGormans.
*The
Ui Fidgenti. Their chiefly families were the
O'Cullanes, O'Kinneallys,
O'Donovans and MacEnerys.
*The
Ulaid
(Old Irish, ) or (Irish language, Modern Irish, ) was a Gaelic Ireland, Gaelic Provinces of Ireland, over-kingdom in north-eastern Ireland during the Middle Ages made up of a confederation of dynastic groups. Alternative names include , which ...
. Their chiefly family was the
MacDonlevys.
Tribes of the Dumnonii or Laigin
As per O'Rahilly's doctrine, the
Dumnonii
The Dumnonii or Dumnones were a Britons (historical), British List of ancient Celtic peoples and tribes, tribe who inhabited Dumnonia, the area now known as Cornwall and Devon (and some areas of present-day Dorset and Somerset) in the further pa ...
or
Laigin
The Laigin, modern spelling Laighin (), were a Gaelic population group of early Ireland. They gave their name to the Kingdom of Leinster, which in the medieval era was known in Irish as ''CĂłiced Laigen'', meaning "Fifth/province of the Leinste ...
were the third wave of Celts to settle in Ireland during the first century BC. In line with this, according to Cairney, from them descended the following Irish tribes. Although it is not possible to prove O'Rahilly's history of the four Celtic invasions of Ireland or that the Dumnonii or Laigin were the third of these invasions, or that the following Irish tribes descended from them, according to historian Sean Duffy, with the exception of the
Ciarraighe Loch na nAirne and the Feara Cualann, the existence of all of the following Irish tribes in around the 7th century is supported by the literature of the time that came to Ireland with Christianity.
*The
Cianacht. Their chiefly families were the O'Connors of
Keenaght and the "race of
Luighne" or "
Lugh
Lugh or Lug (; ) is a figure in Irish mythology. A member of the Tuatha DĂ© Danann, a group of supernatural beings, Lugh is portrayed as a warrior, a king, a master craftsman and a saviour.Olmsted, Garrett. ''The Gods of the Celts and the I ...
" which in turn included the chiefly families of
O'Hara and
O'Gara.
*The Dealbhna Eathra and
Delbhna Nuadat. Their chiefly families were the O'Hanlys, MaCoghlans and O'Conrahys.
*The Saithne. Their chiefly family was the
O'Caseys.
*The
Ciarraighe Loch na nAirne. Their chiefly family was the
O'Kierans.
*The Ciarraighe Luachra. Their chiefly family was the O'Connors of Kerry.
*The
Eile. Their chiefly families were the
O'Carrols of Ely,
O'Mahers,
O'Riordans, and
O'Flanagans.
*The
Ui Failghe. Their chiefly families were the O'Connors of Offaly, O'Mooneys, MacColgans,
O'Hennesseys,
O'Holohans,
O'Dempseys, and
O'Dunnes.
*The Feara Cualann. Their chiefly families were the O'Cullens and
O'Mulryans.
*The
Ui Ceinnsealaigh. Their chiefly families were the
Kavanaghs,
Kinsellas,
O'Murphys, and O'Morchoes.
*The
UĂ DĂșnlainge. Their chiefly families were the
O'Byrnes and
O'Tooles.
*The
Ui Maine. Their chiefs were the
O'Kellys but also included the O'Fahys,
O'Horans,
O'Sheehans,
O'Donnellans,
O'Maddens,
O'Concannons,
O'Mullens,
O'Malleys, O'Naghtens, and
O'Houlihans.
*The
Oirghialla (
AirgĂalla or Oriel). Their chiefly families were the MacBradys,
O'Boylans,
O'Flanagans, O'Mulroonys or Moroneys,
Maguires, MacKerans,
MacAuleys, O'Cassidys,
O'Corrigans, MacManuses,
MacMahons,
MacCanns, O'Hanraghtys,
O'Hanlons, O'Lynns,
MacEvoys, MacDonalds, MacDonells, MacAlisters, MacIans, MacSheeys, MacIntyres, MacDougals, and
Conns.
Tribes of the Gaels or Gaeils
As per O'Rahilly's doctrine, the
Gaels
The Gaels ( ; ; ; ) are an Insular Celts, Insular Celtic ethnolinguistic group native to Ireland, Scotland, and the Isle of Man. They are associated with the Goidelic languages, Gaelic languages: a branch of the Celtic languages comprising ...
or ''Gaeils'' were the fourth and final wave of Celtic settlement in Ireland which took place during the first century BC. In line with this, according to Cairney, from them descended the following Irish tribes. Although it is not possible to prove O'Rahilly's history of the four Celtic invasions of Ireland or that the Gaels or Gaeils were the fourth of these invasions, or that the following Irish tribes descended from them, according to historian Sean Duffy, with the exception of the
Clann CholmĂĄin, Cineal Laoghaire and the Muintear Tadhagain, the existence of all of the following Irish tribes in around the 7th century is supported by the literature of the time that came to Ireland with Christianity.
The North Gaels
*The
Connachta
The Connachta are a group of medieval Irish dynasty, dynasties who claimed descent from the legendary High King of Ireland, High King Conn of the Hundred Battles, Conn Cétchathach (Conn of the Hundred Battles). The modern western Provinces of ...
.
**The
UĂ BriĂșin
The UĂ BriĂșin were a royal dynasty of Connacht. Their eponymous apical ancestor was BriĂłn, son of Eochaid Mugmedon and Mongfind, and an elder half brother of Niall of the Nine Hostages. They formed part of the Connachta, along with th ...
. Their chiefly family was in Gaelic the ''
SĂol Muireadaigh'' which anglicized is Silmurray and which included a number of important families including the O'Connors (
O Connor Donn and
O'Connor Sligo), the
O'Malones, the O'Mulconrys, MacShanlys, MacGoverns,
MacClancys,
O'Rourkes,
O'Reillys, O'Beirnes,
O'Sheridans, O'Carrys, O'Flanagans,
O'Crowleys,
MacDermots,
MacDonaghs,
O'Mulvihills,
MacGeraghtys, and
O'Flahertys.
**The
UĂ Fiachrach.
***The
UĂ Fiachrach Muaidhe (northern). Their main chiefs were the
O'Dowds, but other chiefly families included the
O'Finnegans, O'Keeves, O'Bolans, O'Kearneys, and
O'Quigleys.
***The
UĂ Fiachrach Aidhne (southern). Their main chiefs were the
O'Shaughnessys, but other chiefly families were the O'Heynes, O'Heyne, or
Hynes, O'Clerys,
O'Donnells, O'Houlihans which in some places became Holland and Nolan, and also the
O'Scanlans.
*The
Uà Néill
The UĂ NĂ©ill (; meaning "descendants of Niall") are Irish dynasties that claim descent from Niall NoĂgĂallach (Niall of the Nine Hostages), a historical King of Tara who is believed to have died around c. 405. They are generally divided ...
.
**
Northern Uà Néill
The Northern Uà Néill was any of several dynasties in north-western medieval Ireland that claimed descent from a common ancestor, Niall of the Nine Hostages. Other dynasties in central and eastern Ireland who also claimed descent from Niall ar ...
.
***
CineĂĄl Eoghain. The chiefly family was the
O'Neill dynasty, but also included the
MacLoughlins, O'Branigans,
O'Rahillys of Kerry,
MacMartins of Tyrone,
O'Cahans, MacLachlans, Lamonts, MacSorleys, MacNeills, MacEwens, MacQueens, MacSweens,
MacSweeneys of Ireland, O'Creans,
Creans,
Crehans, Creghans,
O'Donnellys, O'Hegartys,
O'Gormleys,
O'Hagans, and O'Beolans.
***
Cineal Chonaill. Their main chiefs were the
O'Donnell dynasty
The O'Donnell dynasty ( or ''Ă Domhnaill,'' ''Ă Doáčnaill'' ''or Ua Domaill;'' meaning "descendant of DĂłnal") were the dominant Irish clan of the kingdom of Tyrconnell in Ulster in the north of medieval and early modern Ireland.
Naming ...
of
Tyrconnell (TĂr Chonaill), but also included the O'Canannains or O'Canons, O'Muldonys, O'Mulderrys,
O'Friels,
O'Boyles, O'Cullinans, and
O'Dohertys.
***Cineal Cairbre. Their main chiefs were the
O'Brolans.
**
Southern Uà Néill.
***
Clann CholmĂĄin. Their main chiefs were the
O'Melaghlins who were later known as the MacLoughlins of
Meath.
***
Cineal Fiachach. Their main chiefs were the
MacGeoghegans or
O'Molloys.
***
Cineal Laoghaire. Their main chiefs were the O'Quinlans.
***
Fir Teathbha. Their main chiefs were the O'Caharneys,
O'Dallys, MacAwleys, MacCarons,
O'Brennas, and O'Shiels.
***
Muintear Tadhagain. Their chiefs were the O'Caharneys and O'Kearnys or
Foxes
Foxes are small-to-medium-sized omnivorous mammals belonging to several genera of the family Canidae. They have a flattened skull; upright, triangular ears; a pointed, slightly upturned snout; and a long, bushy tail ("brush").
Twelve species ...
.
***The
Four Tribes of Tara
The Four Tribes of Tara was an alliance of powerful clans that consisted of the O'Harts, O'Kelly's, O'Connolly, and the O'Regan. The princes of Tara were also styled princes of Brega, consisting of territory in the modern day counties Meath, Louth ...
: O'Harts,
O'Regans, Mackennas,
O'Higgins.
The South Gaels
*The
Eoghanacht. The chiefly family was the
MacCarthy dynasty
MacCarthy (), also spelled Macarthy, McCarthy or McCarty, is an Irish Irish clans, clan originating from Kingdom of Munster, Munster, an area they ruled during the Middle Ages. It was divided into several septs (branches) of which the MacCarthy ...
, but other families included the O'Meehans,
O'Keeffes,
O'Sullivans and
McGillycuddys.
*The Ui Eachach Mumhan. Their main chiefs were the
O'Callaghans,
O'Donoghue
Donoghue or O'Donoghue is an anglicised form of the Irish language surname Ă Donnchadha or Ă DonnchĂș.
Etymology
The name means "descendant of Donnchadh", a personal name composed of the elements ''donn'' "brown-haired an and ''cath'' "batt ...
s, and
O'Mahonys.
Vikings and Normans in Ireland
Vikings
Vikings were seafaring people originally from Scandinavia (present-day Denmark, Norway, and Sweden),
who from the late 8th to the late 11th centuries raided, pirated, traded, and settled throughout parts of Europe.Roesdahl, pp. 9ïżœ ...
and
Normans
The Normans (Norman language, Norman: ''Normaunds''; ; ) were a population arising in the medieval Duchy of Normandy from the intermingling between Norsemen, Norse Viking settlers and locals of West Francia. The Norse settlements in West Franc ...
are ethnically populations, linked in ancestry. From the 9th to 11th centuries, the Vikings raided and settled in Britain and Ireland. In Ireland the Vikings became completely Gaelicized and established the first towns. The Normans invaded and conquered England in 1066 and later had similar success invading Ireland in the late 12th century. The Normans were the first people to introduce the mounted
knight
A knight is a person granted an honorary title of a knighthood by a head of state (including the pope) or representative for service to the monarch, the church, or the country, especially in a military capacity.
The concept of a knighthood ...
. In Ireland, these "
Old English
Old English ( or , or ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the Early Middle Ages. It developed from the languages brought to Great Britain by Anglo-S ...
" families were influenced just as much as they themselves influenced and have been described as having become "
more Irish than the Irish themselves".
Viking families in Ireland
At least the following three Irish families are believed to be of Viking descent: the
Clan Fearghaill whose chiefs were the
O'Hallorans, the
MacCotters, and the
O'Doyles.
Norman families in Ireland
The following surnames found in Ireland are believed to be of Norman origin and to have arrived following the Norman invasion of Ireland:
Barry, Branne,
Burke,
Butler,
Condon,
Cusak,
Dalton,
Darcy, de Covcy,
Dillon, Fagun,
Fitzgerald, MacGibbon,
French,
Hackett,
Jordan
Jordan, officially the Hashemite Kingdom of Jordan, is a country in the Southern Levant region of West Asia. Jordan is bordered by Syria to the north, Iraq to the east, Saudi Arabia to the south, and Israel and the occupied Palestinian ter ...
,
Keating,
Lacy,
Lynch,
MacCostello, Martin, Nugent, Power,
Purcell, Rothes,
Sarsfield, Wall.
The following surnames are believed to have come to Ireland with the Norman invasion but are believed to have been of
Flemish origin:
Tobin,
Flemming,
Prendergast.
The following surnames are believed to have come to Ireland with the Norman invasion but are believed to have been of
Welsh origin:
Roche
F. Hoffmann-La Roche AG, commonly known as Roche (), is a Switzerland, Swiss multinational corporation, multinational holding healthcare company that operates worldwide under two divisions: Pharmaceuticals and Diagnostics. Its holding company, ...
,
Blake,
Joyce,
MacQuillan,
Rice
Rice is a cereal grain and in its Domestication, domesticated form is the staple food of over half of the world's population, particularly in Asia and Africa. Rice is the seed of the grass species ''Oryza sativa'' (Asian rice)âor, much l ...
, Taffe,
Walsh
Walsh may refer to:
People and fictional characters
* Walsh (surname), including a list of people and fictional characters
Places Australia
* Mount Walsh, Mount Walsh National Park
Canada
* Fort Walsh, one of the first Royal Canadian Mounted ...
, Savage.
End of the clan system

In the 16th century,
English common law
English law is the common law legal system of England and Wales, comprising mainly criminal law and civil law, each branch having its own courts and procedures. The judiciary is independent, and legal principles like fairness, equality bef ...
was introduced throughout Ireland, along with a centralised royal administration in which the county and the sheriff replaced the "country" and the clan chief.
When the
Kingdom of Ireland
The Kingdom of Ireland (; , ) was a dependent territory of Kingdom of England, England and then of Kingdom of Great Britain, Great Britain from 1542 to the end of 1800. It was ruled by the monarchs of England and then List of British monarchs ...
was created in 1541, the Dublin administration wanted to involve the Gaelic chiefs into the new entity, creating new titles for them such as the
Baron Upper Ossory
Baron Upper Ossory was a title in the Peerage of Ireland. It was created on 11 June 1541 for Barnaby Fitzpatrick. This was in pursuance of the Surrender and regrant policy of King Henry VIII. Under the policy, Gaelic chiefs were actively encou ...
,
Earl of Tyrone, and
Baron Inchiquin. In the process, they were granted new coats of arms from 1552. The associated policy of
surrender and regrant
During the Tudor conquest of Ireland (c.1540â1603), "surrender and regrant" was the legal mechanism by which Irish clans were to be converted from a power structure rooted in clan and kin loyalties, to a late-Feudalism, feudal system under t ...
involved a change to succession to a title by the European system of
primogeniture
Primogeniture () is the right, by law or custom, of the firstborn Legitimacy (family law), legitimate child to inheritance, inherit all or most of their parent's estate (law), estate in preference to shared inheritance among all or some childre ...
, and not by the Irish
tanistry, where a group of male cousins of a chief were eligible to succeed by election.
The early 17th century was a watershed in Ireland. It marked the destruction of Ireland's ancient Gaelic aristocracy following the Tudor re-conquest and cleared the way for the
Plantation of Ulster
The Plantation of Ulster (; Ulster Scots dialects, Ulster Scots: ) was the organised Settler colonialism, colonisation (''Plantation (settlement or colony), plantation'') of Ulstera Provinces of Ireland, province of Irelandby people from Great ...
. In 1607 the senior Gaelic chiefs of Ulster left Ireland to recruit support in Spain but failed, and instead eventually arrived in Rome where they remained for the rest of their lives . After this point, the English authorities in Dublin established real control over all of Ireland for the first time, bringing a centralised government to the entire island, and successfully disarmed the native clans and their lordships.
Later developments and "revival"
Clans of Ireland is an Irish non-governmental organisation established in 1989 with the aim of authenticating, representing and co-ordinating the activities of modern Irish clan organisations. It has operated under the patronage of the
President of Ireland
The president of Ireland () is the head of state of Republic of Ireland, Ireland and the supreme commander of the Defence Forces (Ireland), Irish Defence Forces. The presidency is a predominantly figurehead, ceremonial institution, serving as ...
since 2012,
and is accredited as a "civil society
NGO" by the United Nations.
It performs research, promotes clan rallies, and advances DNA studies.
The
Standing Council of Scottish Chiefs signed a Memorandum of Understanding with Clans of Ireland in 2013 at Christchurch Cathedral, Dublin. As part of the agreement they agreed to mutually recognise each other's authority.
See also
*
List of Irish clans in Ulster
*
Scottish clan
A Scottish clan (from Scottish Gaelic , literally 'children', more broadly 'kindred') is a kinship group among the Scottish people. Clans give a sense of shared heritage and descent to members, and in modern times have an official structure r ...
*
List of Scottish clans
*
List of ancient Celtic peoples and tribes
This is a list of ancient Celtic peoples and tribes.
Continental Celts
Continental Celts were the Celtic peoples that inhabited mainland Europe and Anatolia (also known as Asia Minor). In the 3rd and 2nd centuries BC, Celts inhabited a large ...
*
Celtic peoples
Notes
References
Bibliography
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External links
Clans of IrelandFitzpatrick Clan SocietyThe Fitzpatrick â Mac Giolla PhĂĄdraig Clan Society
{{DEFAULTSORT:Irish Clans