Kalgan

Zhangjiakou (), also known as Kalgan and by several other names, is a prefecture-level city in northwestern Hebei province in Northern China, bordering Beijing to the southeast, Inner Mongolia to the north and west, and Shanxi to the southwest. In 2020, its population was 4,118,908 inhabitants, with an area of , divided into 17 counties and districts. The built-up (''or metro'') area, made of Qiaoxi, Qiaodong, Chongli, Xuanhua, Xiahuayuan Districts, is largely conurbated, with 1,413,861 inhabitants in 2020 in an area of .

Since ancient times, Zhangjiakou has been a stronghold of military significance and vied for by multiple sides, hence it is nicknamed the Northern Gate of Beijing. Due to its strategic position on several important transport arteries, it is a critical node for travel between Hebei and Inner Mongolia and connecting northwest China, Mongolia, and Beijing. Dajingmen, an important gate and junction of the Great Wall of China, is located here.

In the south, Zhangjiakou is largely cultivated for agricultural use. In the north, Bashang is a part of the Mongolian plateau and dominated by grasslands. The forest coverage reaches 37%, earning Zhangjiakou the title of National Forest City. According to the Ministry of Environmental Protection, Zhangjiakou has the freshest air and the least PM 2.5 pollution of all Chinese cities north of the Yellow River. Zhangjiakou also possesses 4.6% of China's wind energy resources, and the city ranks second in solar energy use. Zhangjiakou was one of the host cities at the 2022 Winter Olympics.

Names

Zhangjiakou is the atonal pinyin romanization of the Chinese name written in traditional characters and in simplified ones, meaning " pass of the Zhang family". It is written in tonal pinyin and was formerly romanized as Chang-chia-k'ou in Wade–Giles and as Changchiakow in Postal Map romanization. The name is a clipping of Zhangjiakoubu
(), " earthwork fortress of the Zhang family", named in honor of the Ming-era official Zhang Wen () who directed its construction from 1429. During China's Republican Era, the town was also known in Chinese as Zhangyuan (), "the Zhang Wall".

Until the mid-20th century, Zhangjiakou was more often known to Europeans as Kalgan from its classical Mongolian name meaning barrier or beam gate, but actually a shortened form of the full name "assembly" or "meeting gate" from its importance along Sino-Mongolian trade routes. The modern Mongolian forms of these names are () and (). The Manchu form of the name was ().

During the Ming dynasty, when the city was a major military outpost against the Northern Yuan, it was also known as Wucheng ), "Martial" or "War Town". Because of its strategic position above and northwest of Beijing, Zhangjiakou has been nicknamed "Beijing's Northern Door".

History

Pre-Qin era

There are many paleolithic remains like Nihewan, Xiaochangliang, and Maquangou located in Guyuan county, which indicated human activities dating back possibly 2 million years ago.

Around 2500 BC, the legendary ancestors of Chinese people, Huangdi, Yandi, and Chiyou used to live in the area of Zhuolu Town, and later fought the Battle of Zhuolu and Battle of Banquan, amalgamating different tribes into a single Huaxia tribe, thus beginning Chinese history.

During Spring and Autumn period, Xiongnu and Donghu people inhabited the northern area while Yan State (since around 11th century BC) and Dai state (since 7th century BC) occupied the southern area. In 475 BC, Dai was occupied by Zhao Wuxu of Zhao State. In 300 BC, King Wuling of Zhao established Dai Commandery, managing the area of ancient Dai state with its administrative center in Dai, currently Daiwangcheng, Yu County. During the same period of time, King Zhao of Yan sent General Qin Kai who was once captured by Donghu people and thus became familiar with their tactics to defeat Donghu. Following that, Yan State built Great Wall in its border extending from Zaoyang (currently northeast of Xuanhua) to Xiangping (currently north of Liaoyang). In 283 BC, King Zhao established Shanggu Commandery. In 265 BC, Li Mu, a famous general of Zhao, commanded and deployed troops in Dai to protect against Xiongnu. After arriving in Dai, initially Li Mu banned any counterattack against Xiongnu to preserve the strength for years, which however incurred the discontent of King of Zhao. As a result, Li Mu was sacked. Following Zhao troops' defeat later, King of Zhao reinstated Li Mu. Viewing Zhao troops as cowards, Xiongnu grew arrogant and underestimated Zhao's strength. Finally, Li Mu led troops and ambushed Xiongnu, causing hundreds of thousands of casualties and great damage of Xiongnu, thus ensuring decades of peace in Zhao's borderlands.

In 228 BC, Wang Jian, a Qin general defeated Zhao army and occupied its capital, Handan. Jia, a son of Zhao king, escaped to Dai, currently northeast of Yu County and declared himself as the King of Dai. In alliance with Xi, King of Yan, the combined army, commanded by Crown Prince Dan was defeated at Yishui. In 222 BC, Wang Ben, a Qin general defeated Yan state and then, attacked Dai. He captured Jia and ended Dai as a state. Jia feared humiliation and committed suicide.

Qin–Han era

During the Qin dynasty, Shihuangdi sent Meng Tian, commanding 300,000 troops to defend his empire from Xiongnu's attacks. They spent 10 years connecting the Great Wall of Yan, Qin and Zhao, thus building Great Wall of Qin, the first Great Wall of 10,000 li, its 80-kilometer-long relics currently located in Batou (), or Erdaogou () in local slang, to the north of Zhangjiakou downtown area. The southern area of Zhangjiakou was under jurisdiction of Dai Commandery and Shanggu Commandery.

During the Han dynasty, most part of the area belonged to You Prefecture while some parts belonged to Wuhuan