Great Wall in the context of "Fortifications"

China, officially the People's Republic of China (PRC), is a country in East Asia. With a population exceeding 1.4 billion, it is the second-most populous country after India, representing 17% of the world population. China borders fourteen countries by land across an area of 9.6 million square kilometers (3,700,000 sq mi), making it the third-largest country by area. The country is divided into 33 province-level divisions: 22 provinces, 5 autonomous regions, 4 municipalities, and 2 semi-autonomous special administrative regions. Beijing is the capital, while Shanghai is the most populous city by urban area and largest financial center.

China saw the first humans in the region arriving during the Paleolithic era. By the 2nd millennium BCE dynastic states had emerged in the Yellow River basin. The 8th–3rd centuries BCE saw a breakdown in the authority of the Zhou dynasty, accompanied by the emergence of administrative and military techniques, literature and philosophy. In 221 BCE, China was unified under an emperor, ushering in two millennia of imperial dynasties. With the invention of gunpowder and paper, the establishment of the Silk Road, and the Great Wall, Chinese culture flourished and has heavily influenced its neighbors and lands further afield. China began to cede parts of the country in the 19th century, to European powers by a series of unequal treaties. The 1911 Revolution overthrew the Qing dynasty and the Republic of China was established the following year. The country was unstable and fragmented during the Warlord Era, which ended upon the Northern Expedition conducted by the Kuomintang to reunify the country.

The Han–Xiongnu Wars or Sino-Xiongnu Wars, were a series of military conflicts fought from 133 BC to 89 AD between the agrarian Chinese Han Empire and the nomadic Xiongnu confederacy, although extended conflicts can be traced back as early as 200 BC and as late as 188 AD.

The Chinese civilization initially clashed with Inner Asian nomadic tribes (then collectively known as Di) that would later become the Xiongnu during the Warring States period, and various northern states built elongated fortifications (which later became the Great Wall) to defend against raids down from the Mongolian Plateau. The unified Qin dynasty, who conquered all other states under Emperor Qin Shi Huang, dispatched General Meng Tian in 215 BC in a successful campaign to expel the Xiongnu from the Ordos region (which was often used as a staging area to threaten Qin's Guanzhong heartland). However, the subsequent civil wars following the Qin dynasty's collapse gave the Xiongnu tribes, who were then unified into a large confederacy under Modu Chanyu, the opportunity to reinvade the Ordos region. After the Han dynasty was established in 202 BC, Emperor Gao tried to fight off Xiongnu invasions but had himself trapped in an ambush during the Battle of Baideng, and a truce was negotiated by bribing Modu's wife, thus ending first Han–Xiongnu War. Decades of de jure peace then followed with the Chinese gifting "harmony via marriage" to appease the Xiongnu, who still routinely raided Chinese borderlands.

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 km (2,033 sq mi).In 2024, the registered population of the whole region is 208.896 million

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.

Yumen Pass (simplified Chinese: 玉门关; traditional Chinese: 玉門關; pinyin: Yùmén Guān; Uyghur: قاش قوۋۇق, Qash Qowuq), or Jade Gate or Pass of the Jade Gate, is the name of a pass of the Great Wall located west of Dunhuang in today's Gansu Province of China. During the Han dynasty (202 BC – AD 220), this was a pass through which the Silk Road passed, and was the one road connecting Central Asia with East Asia (China), the former called the Western Regions. Just to the south was the Yangguan pass, which was also an important point on the Silk Road. These passes, along with other sites along the Silk Road, were inscribed in 2014 on the UNESCO World Heritage List as the Silk Roads: the Routes Network of Chang'an-Tianshan Corridor World Heritage Site. The pass is at an elevation of 1400 meters.