Italia (the Latin and Italian name for the Italian Peninsula) was the homeland of the Romans and metropole of Rome's empire in classical antiquity. According to Roman mythology, Italy was the ancestral home promised by Jupiter to Aeneas of Troy and his descendants, whose descendants were the founders of Rome. Aside from the legendary accounts, Rome was an Italic city-state that changed its form of government from kingdom to republic and then grew within the context of a peninsula dominated by the Celts in the North, the Etruscans and Umbrians in the Centre, and the Messapians (Illyrian Colonies) and Greeks colonies in the south.
The consolidation of Italy into a single entity occurred during the Roman expansion in the peninsula, when Rome formed a permanent association with most of the local tribes and cities. The strength of the Italian confederacy was a crucial factor in the rise of Rome, starting with the Punic and Macedonian wars between the 3rd and 2nd century BC. As provinces were being established throughout the Mediterranean, Italy maintained a special status which made it "not a province, but the Domina (ruler) of the provinces". Such a status meant that Roman magistrates exercised the Imperium domi (police power) within Italy, rather than the Imperium militiae (military power) used abroad. Italy's inhabitants had Latin Rights as well as religious and financial privileges.
The period between the end of the 2nd century BC and the 1st century BC was turbulent, beginning with the Servile Wars, continuing with the opposition of aristocratic élite to populist reformers and leading to a Social War in the middle of Italy. However, Roman citizenship was recognized to the rest of the Italics by the end of the conflict and then extended to Cisalpine Gaul when Julius Caesar became Roman Dictator. In the context of the transition from Republic to Principate, Italy swore allegiance to Octavian Augustus and was then organized in eleven regions from the Alps to the Ionian Sea.
More than two centuries of stability followed, during which Italy was referred to as the rectrix mundi (queen of the world) and omnium terrarum parens (motherland of all lands). Several emperors made notable accomplishments in this period: Claudius incorporated Britain into the Roman Empire, Vespasian subjugated the Great Revolt of Judea and reformed the financial system, Trajan conquered Dacia and defeated Parthia, and Marcus Aurelius epitomized the ideal of the philosopher king.
The crisis of the third century hit Italy particularly hard and left the eastern half of the Empire more prosperous. In 286 AD the Roman Emperor Diocletian moved the capital of the Western Roman Empire from Rome to Mediolanum. Nevertheless, the islands of Corsica, Sardinia, Sicily and Malta were added to Italy by Diocletian in 292 AD, and Italian cities such as Mediolanum and Ravenna continued to serve as capitals for the West.
The Bishop of Rome gained importance during Constantine's reign and was given religious primacy with the Edict of Thessalonica under Theodosius I. Italy was invaded several times by the barbarians and fell under the control of Odoacer, when Romulus Augustus was deposed in 476 AD. In the sixth century, Italy's territory was divided between the Eastern Roman Empire and the Germanic peoples.[further explanation needed] After that, Italy remained divided until 1861, when it was reunited by the House of Savoy in the Kingdom of Italy, which became the present-day Italian Republic in 1946.