Shanhaiguan District in the context of "Hebei"

The Shanhai Pass (simplified Chinese: 山海关; traditional Chinese: 山海關; pinyin: Shānhǎi Guān; lit. 'Mountain Sea Pass') is a major fortified gateway at the eastern end of the Great Wall of China and one of its most crucial fortifications, as the pass commands the narrowest choke point in the strategic Liaoxi Corridor, an elongated coastal plain between the Yan Mountains foothills and the Bohai Sea, which is the only easily traversable landway between North and Northeast China. It is located in present-day Shanhaiguan District, Qinhuangdao, Hebei province, on the east bank of the Shi River, with defensive walls stretching from the Yan Mountains all the way to the shores of the Liaodong Bay.

Throughout Chinese history, garrisons around the pass served as frontline defensive outposts against raids and incursions into the North China Plain by various non-Sinitic ethnic groups from the Northeast (also known as Manchuria since the 19th century), including the Dongyi, Donghu (Xianbei and Wuhuan), Khitan and Jurchen (Manchus). The current Shanhai Pass was built during the early Ming dynasty as the easternmost fortification of the Ming Great Wall, and was extensively reinforced after Yongle Emperor moved the capital from Nanjing to Beijing following the Jingnan campaign, making it the most important defensive barrier in all of China, as it shielded the heartland region around the imperial capital. The pass' strategic location dictated that without mounting a costly direct siege, the only way an invading army can get past the pass' defense was to circumvent it around the north through a few treacherously narrow mountain passes deep within the Yan Mountains, which would make it very difficult to maintain supply lines and thus any sizeable invasions. This defensive significance therefore earned the pass the famous nickname "Greatest Pass Under Heaven" (天下第一关).

Hebei is a province in North China. It is China's sixth-most populous province, with a population of over 75 million people. Shijiazhuang is the capital city. It borders Shanxi to the west, Henan to the south, Shandong and Liaoning to the east, and Inner Mongolia to the north; in addition, Hebei entirely surrounds the direct-administered municipalities of Beijing and Tianjin on land. Its population is 96% Han Chinese, 3% Manchu, 0.8% Hui, and 0.3% Mongol. Varieties of Chinese spoken include Jilu Mandarin, the Beijing dialect of Mandarin, and Jin Chinese.

During the Spring and Autumn and Warring States periods (771–226 BC), the region was ruled by the states of Yan and Zhao. During the Yuan dynasty (1271–1368), the region was called Zhongshu. It was called North Zhili during the Ming dynasty (1368–1644), and simply Zhili during the Qing dynasty (1644–1912). The modern province of Hebei was created in 1928. Five UNESCO World Heritage Sites can be found in the province: the Great Wall of China, Chengde Mountain Resort, Grand Canal, Eastern Qing tombs, and Western Qing tombs. It is also home to five National Famous Historical and Cultural Cities: Handan, Baoding, Chengde, Zhengding and Shanhaiguan.