Battle of Mobei - Background

Background

Military tension had for a long time existed between ancient China and the northern "barbarians", mainly because the fertile lands of the prosperous agricultural civilization presented attractive targets for the militaristic nomadic tribes. Throughout ancient Chinese history, protecting the northern borders from nomadic raids had been a military priority. During the Zhou Dynasty, northern vassal states such as Yan, Zhao and Qin resorted to defensive strategies, constructing elongated fortresses that served as the precursors of the Great Wall of China. During the Qin Dynasty, the first emperor Qin Shi Huang conscripted thousands of civilian labourers to perfect the Great Wall in order to reinforce military campaigns along the northern border.

Han Dynasty China and the nomadic Xiongnu Empire had a very bitter relationship. The Xiongnu were initially a group of steppe tribes kept in check by the Qin Empire's military offensives under General Meng Tian. With the collapse of the Qin Dynasty and the subsequent Chinese civil war, the Xiongnu gained the opportunity to become unified under Modu Shanyu and quickly expanded into a powerful tribal confederacy that ruled over a vast territory across Central and East Asia. The Xiongnu then invaded and occupied the fertile Hetao Grassland. When the Chu-Han contention concluded, Emperor Gao recognized the threat posed by its hostile northern neighbour and in 200 BC launched a massive campaign. After the Han army was lured into an ambush and encircled by 300,000 elite Xiongnu cavalry for seven days, the siege was relieved only after messengers were sent to bribe the Shanyu's wife. Following this failure, the Han emperor realized that the nation, just recovered from a massive civil war, was not yet strong enough to confront the Xiongnu and therefore resorted to the so-called "marriage alliance", or heqin, in order to ease hostility and buy time to strengthen the nation. Despite the humiliating periodic heqin and giving of gifts, the Han borders were still frequently raided by Xiongnu forces over the next seven decades.

During his reign, Emperor Wu of Han decided that the nation was finally strong enough to solve the Xiongnu problem. The "peaceful" atmosphere was broken in 133 BC after a large ambush operation was staged at Mayi but aborted after the Xiongnu discovered the trap and retreated. In 129 BC, the Han forces had their first proper victory against the Xiongnu under the command of the young Wei Qing with a long-distance raid on the Xiongnu holy site at Longcheng (蘢城). Over the next ten years, Emperor Wu repeatedly deployed Wei and his vigorous nephew Huo Qubing against Xiongnu forces thus recapturing large areas of land and dealing devastating blows.

Evicted by the defeats, Yizhixie Chanyu (伊稚邪) took Zhao Xin's advice, and the Xiongnu tribes retreated to the north of the Gobi Desert, hoping that the barren land would serve as a natural barrier against Han offensives. In 119 BC, Emperor Wu planned a massive expeditionary campaign. Chinese forces were deployed in two columns, each consisting of 50,000 cavalry and over 100,000 infantry. Wei Qing and Huo Qubing served as the supreme commanders, and set off from Dai Prefecture (代郡) and Dingxiang (定襄).