Zhangjiakou

Zhangjiakou (/ˈdʒɑːŋdʒiˈɑːˈkoʊ/), 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 36,861.56 square kilometres (14,232.33 sq mi), 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 5,266 km² (2,033 sq mi).

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.

Zhangjiakou is the atonal pinyin romanization of the Chinese name written 張家口 in traditional characters and 张家口 in simplified ones, meaning "pass of the Zhang family". It is written Zhāngjiākǒu 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 (张家口堡; 張家口堡; Zhāngjiākǒubǔ), "earthwork fortress of the Zhang family", named in honor of the Ming-era official Zhang Wen (张文; 張文; Zhāng Wén) who directed its construction from 1429. During China's Republican Era, the town was also known in Chinese as Zhangyuan (张垣; 張垣; Zhāngyuán), "the Zhang Wall".

Until the mid-20th century, Zhangjiakou was more often known to Europeans as Kalgan from its classical Mongolian name Qaɣalɣan (ᠬᠠᠭᠠᠯᠭᠠᠨ), meaning barrier or beam gate, but actually a shortened form of the full name Čiɣulaltu Qaɣalɣa (ᠴᠢᠭᠤᠯᠠᠯᠲᠤ
ᠬᠠᠭᠠᠯᠭ᠎ᠠ), "assembly" or "meeting gate" from its importance along Sino-Mongolian trade routes. The modern Mongolian forms of these names are Haalgan (Хаалган) and Chuulalt Haalga (Чуулалт Хаалга). The Manchu form of the name was Imiyangga Jase (ᡳᠮᡳᠶᠠᠩᡤᠠ
ᠵᠠᠰᡝ).

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

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.