Han–Xiongnu War
In 119 BC, when the Xiongnu suffered a catastrophic defeat by the Han armies, the Chanyu moved his court (located in present-day Inner Mongolia) to another location north. This had the desired result that the Xiongnu were separated the Wuhuan people, which also prevented the Xiongnu from exacting many resources from the Wuhuan. The Han court placed the Wuhuan in tributary protection and resettled them in five northeastern commandaries, namely Shanggu, Yuyang, Youbeiping (present-day Hebei), Liaoxi, and Liaodong (present-day Liaoning). A new office, the Colonel-Protector of the Wuhuan, was established (near present-day Beijing) in order to prevent contact between the Wuhuan with the Xiongnu and to use them to monitor the Xiongnu activities. Nevertheless, the effective Han control over the Wuhuan was lacking through much of the Western Han period, since the Xiongnu had considerable military and political influence over the Wuhuan while relations between the Wuhuan and Han often remained strained at best. This can be exemplified by a situation in 78 BC, when the Xiongnu led a punitive campaign against the Wuhuan, resulting in General Fan Mingyou (范明友) leading a Han army to impede further incursions. When they learned that the Xiongnu had left by the time the army arrived, the Han court ordered Fan to attack the Wuhuan instead, killing 6000 Wuhuan men and three chieftains, since the Wuhuan had recently raided Han territory. Only in 49 AD, when 922 Wuhuan chieftains submitted during Emperor Guangwu's reign, did many of the Wuhuan tribes come under tributary system of the Han empire. The Han court provided for the Wuhuan and in return the Wuhuan tribes guarded the Han frontier against the Xiongnu and other nomadic peoples.
Han–Xiongnu War
In 89 AD, General Dou Xian led a Han expedition against the Northern Xiongnu. The army advanced from Jilu, Manyi, and Guyang in three great columns. In the summer of 89, the forces—comprising a total of 40,000 troops—assembled at Zhuoye Mountain. Near the end of the campaign, Dou's forces chased the Northern Chanyu into the Altai Mountains, killing 13,000 Xiongnu and accepting the surrender of 200,000 Xiongnu from 81 tribes. A light cavalry of 2000 was sent towards the Xiongnu at Hami, capturing the region from them. General Dou Xian marched with his troops in a triumphal progress to the heartland of the Northern Xiongnu's territory and engraved an inscription commemorating the victory on Mount Yanran, before returning to Han. The Han victory in the campaign of 89 AD resulted in the destruction of the Xiongnu state. In 2017, a joint Sino-Mongolian archaeological expedition rediscovered the Inscription of Yanran in the Khangai Mountains of central Mongolia.