Zhangjiakou (/ˈdʒɑːŋdʒiˈɑːˈkoʊ/),[2] also known as Kalgan[3] 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.

The built-up (or metro) area made of Qiaoxi, Qiaodong, Chongli, Xuanhua, Xiahuayuan Districts largely being conurbated had 1,413,861 inhabitants in 2020 on 5,266 km2 (2,033 sq mi).

[4] Since ancient times, Zhangjiakou has been a stronghold of military significance and vied for by multiple sides, hence nicknamed the Northern Gate of Beijing.

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 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".

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".

[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.

Following that, Yan State built Great Wall in its border extending from Zaoyang (currently northeast of Xuanhua) to Xiangping (currently north of Liaoyang).

[7]: 15–16  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.

In alliance with Xi, King of Yan, the combined army, commanded by Crown Prince Dan was defeated at Yishui.

In 937, in order to enlist the help from Khitan people to defeat Later Tang, Shi Jingtang of Later Jin (Five Dynasties) agreed to cede Sixteen Prefectures to Khitan, later Liao dynasty, in which Xinzhou (新州, present Zhuolu), Weizhou (妫州, Huailai), Wuzhou (武州), Yuzhou (蔚州) were included.

In 951, Yelu Ruan, the Emperor Shizong of Liao intended to attack Later Zhou in the south despite the reluctance of many subordinate tribes.

She often stationed troops in Yanzicheng (燕子城present Zhangbei), the name of which is believed to derive from Xiao Yanyan in preparations for the War against Song.

Kublai established Jinlianchuan Mufu (金蓮川幕府), enlisting many talent of Han people like Liu Bingzhong to assist his governance.

In August 1329, during Tianli Incident following the War of the Two Capitals, the new emperor Khutughtu Khan Kusala was poisoned to death by El Temür in Zhongdu.

On September 1, 1449, while retreating from the campaign against Mongols (Oirats), the 500,000-man army was defeated and the Emperor Yingzong of Ming was captured by chasing Mongolian troops in Huailai County, which was later called Tumu Crisis.

From 1545, Xuanda Governor Weng Wanda (宣大總督翁萬達) began building Xuanfu Great Wall, reaching 462 li (231 km) next year.

In 1545, he built Great Walls again, reaching 169 li (84.5 km), effectively defending the area of Mongol cavalry's invasion.

In early autumn long lines of camels would come in from all quarters for the conveyance of the tea chests from Zhangjiakou to Kyakhta across the Gobi Desert.

The 1911 Encyclopædia Britannica noted that, in Kalgan, "the ordinary houses have an unusual appearance, from the fact that they are mostly roofed with earth and become covered with green-sward" and that "on the way to Peking the road passes over a beautiful bridge of seven arches, ornamented with marble figures of animals".

In the early 1960s, at the height of Sino-Soviet tensions, Zhangjiakou was considered one of the most important cities in China for military strategy reasons.

[10] Lying in between the Mongolian Plateau and the North China Plain, Zhangjiakou has a somewhat rugged topography characterized by high mountains, deep valleys, and rocky pathways.

As a result, it serves as a perfect natural screen for Beijing, which has made it a strategic priority militarily since ancient times.

[citation needed] As a place where water resources for Beijing is located, ecological and sustainable development have been emphasized by local government.

Possessing diverse landforms, such as plains, hills, mountains, basins and grasslands, Zhangjiakou is an ideal place for holidays, entertainment sightseeing for neighbour middle class and can provide tourists with a variety of experiences.

In winter, tourists can ski in Chongli Mountains; in spring, they can visit historical sites; in summer, visitors can sleep in Mongolian yurts on Zhangbei Grassland, where annual musical events were held and taste fresh mutton; while in autumn, visitors can taste Huailai wine and take a bath in nearby hot springs.

[18] Due to its comparatively late implementation Reform and Opening policies, the scale of foreign investment in Zhangjiakou is not quite large.

[20] Due to several factors including the hosting of 2022 Winter Olympic Games with its concomitant expansion of infrastructure, the opening of high-speed railway in December 2019, the national strategy of coordinated development of Beijing-Tianjin-Hebei, the ratification of building a national demonstration zone of renewable energy by State Council of the People's Republic of China, Zhangjiakou economy is expected to undergo unprecedented advance in the coming years.

The snow season lasted for five months from November, during which Chongli has hosted thirty-six competitions and activities, such as Far East Cup and Children Skiing International Festival.