Military history of the Three Kingdoms
By the time of the Three Kingdoms period the Xiongnu had already ceased to be a major power. Their last stand as a steppe empire was in 89 when Dou Xian led an army of 45,000 and decisively defeated them at the Battle of the Altai Mountains. The Xiongnu Empire was replaced by a loose confederation of disorganized Xianbei tribes, who were nonetheless highly aggressive and proved problematic to their southern neighbors. A southern branch of the Xiongnu split off from their northern neighbors in 50 AD and continued to exist as a Han puppet state in Bing Province. However, in 188 the Xiuchuge clan rebelled against their Chanyu, Qiangqu, for sending troops to aid the Han against the rebels Zhang Ju and Zhang Chun. They replaced Qiangqu with his son Yufuluo, who's hold on power was tenuous, and he was ousted over a marquis of the Xubu clan. When the marquis of Xubu died the next year an elderly king became the nominal head of state without the title of Chanyu and the Southern Xiongnu ceased to exist as a coherent entity. In 216 the Xiongnu of the Ordos were settled but the region remained outside the jurisdiction of Cao Wei's administration.
Huns
Since Joseph de Guignes in the , modern historians have associated the Huns who appeared on the borders of Europe in the with the Xiongnu who had invaded China from the territory of present-day Mongolia between the and the . Due to the devastating defeat by the Chinese Han dynasty, the northern branch of the Xiongnu had retreated north-westward; their descendants may have migrated through Eurasia and consequently they may have some degree of cultural and genetic continuity with the Huns. Scholars also discussed the relationship between the Xungnu, the Huns, and a number of people in central Asia were also known as or came to be identified with the name "Hun" or "Iranian Huns", the Chionites, the Kidarites, and the Hephthalites (or White Huns) being the most prominent.