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.
History of Central Asia
In the 2nd and 1st millennia BC, a series of large and powerful states developed on the southern periphery of Central Asia (the Ancient Near East). These empires launched several attempts to conquer the steppe people, but met with only mixed success. The Median Empire and Achaemenid Empire both ruled parts of Central Asia. The Xiongnu Empire (209 BC-93 (156) AD) may be seen as the first central Asian empire which set an example for later Göktürk and Mongol empires. Xiongnu's ancestor Xianyu tribe founded Zhongshan state (c. 6th century BC – c. 296 BC) in Hebei province, China. The title chanyu was used by the Xiongnu rulers before Modun Chanyu so it is possible that statehood history of the Xiongnu began long before Modun's rule.