Xiongnu
Full-scale war broke out in autumn 129 BC, when 40,000 Chinese cavalry made a surprise attack on the Xiongnu at the border markets. In 127 BC, the Han general Wei Qing retook the Ordos. In 121 BC, the Xiongnu suffered another setback when Huo Qubing led a force of light cavalry westward out of Longxi and within six days fought his way through five Xiongnu kingdoms. The Xiongnu Hunye king was forced to surrender with 40,000 men. In 119 BC both Huo and Wei, each leading 50,000 cavalrymen and 100,000 footsoldiers (in order to keep up with the mobility of the Xiongnu, many of the non-cavalry Han soldiers were mobile infantrymen who traveled on horseback but fought on foot), and advancing along different routes, forced the "chanyu" and his court to flee north of the Gobi Desert. Major logistical difficulties limited the duration and long-term continuation of these campaigns. According to the analysis of Yan You (嚴尤), the difficulties were twofold. Firstly there was the problem of supplying food across long distances. Secondly, the weather in the northern Xiongnu lands was difficult for Han soldiers, who could never carry enough fuel. According to official reports, the Xiongnu lost 80,000 to 90,000 men, and out of the 140,000 horses the Han forces had brought into the desert, fewer than 30,000 returned to China.
Turkic migration
Qin's campaign against the Xiongnu of 215 BCE kept the Xiongnu at bay, driving them out of and seizing the Ordos region. Problems re-emerged after the Qin Dynasty. The Xiong-nu attacked Shanxi of the Han in 201 BCE. Emperor Gaozu of Han bought them off with jade, silk and a Chinese wife for the Shanyu, or leader. Relations with the Xiongnu continued to be troubled and in 133 BC Emperor Wu of Han proceeded against them with 300,000 men. Eighty-one years and fourteen expeditions later in 52 BC the southern Xiongnu surrendered and the northern desisted from raiding. The Han Dynasty military expeditions continued near the frontier of China, in the Han–Xiongnu War, and in 89 AD the Xiongnu state was defeated and soon ended.