Xiongnu, nomadic pastoral people who at the end of the 3rd century bce formed a great tribal league that was able to dominate much of Central Asia for more than 500 years. China’s wars against the Xiongnu, who were a constant threat to the country’s northern frontier throughout this period, led to the Chinese exploration and conquest of much of Central Asia.
The Xiongnu first appear in Chinese historical records about the 5th century bce, when their repeated invasions prompted the small kingdoms of North China to begin erecting what later became the Great Wall. The Xiongnu became a real threat to China after the 3rd century bce, when they formed a far-flung tribal confederation under a ruler known as the chanyu, the rough equivalent of the Chinese emperor’s designation as the tianzi (“son of heaven”). They ruled over a territory that extended from western Manchuria (Northeast Provinces) to the Pamirs and covered much of present Siberia and Mongolia. The Xiongnu were fierce mounted warriors who were able to muster as many as 300,000 horseback archers on their periodic intrusions into North China, and they were more than a match for the much less-maneuverable chariots of the Chinese. The completion of the Great Wall along the whole of China’s northern frontier during the Qin dynasty (221–206 bce) slowed but did not stop the Xiongnu. The early Han dynasty rulers attempted to control them by marrying their leaders to Chinese princesses. But Xiongnu raids against China continued periodically until the Han emperor Wudi (reigned 141/140–87/86 bce) initiated a fiercely aggressive policy against the nomads, sending expeditions into central China to outflank them and to negotiate alliances with their enemies. These expeditions led to the Chinese conquest of the state of Chosŏn in northern Korea and southern Manchuria and the Chinese exploration of Turkistan.
In 51 bce the Xiongnu empire split into two bands: an eastern horde, which submitted to the Chinese, and a western horde, which was driven into Central Asia. Chinese expeditions against the former group in the 1st century ce again resulted in the temporary extension of Chinese control to much of what constitutes the present-day northwestern provinces of Gansu and Xinjiang. But as the Han dynasty began to weaken, the Chinese began to hire Xiongnu generals to patrol China’s northern borders, and these semi-Sinicized tribesmen frequently turned on their masters, particularly after the fall of the Han (220 ce) and the establishment of a number of small dynasties.
In 304 ce one of these Xiongnu generals, Liu Yuan, who claimed descent from the early Han emperors through a Chinese princess given in marriage to a Xiongnu chief, declared himself the first ruler of the Northern Han dynasty, also known as the Former Zhao. In 329, however, the dynasty was overthrown by another Xiongnu general, Shi Le, who in 319 had established his own Later Zhao dynasty, which was also short-lived.
Xiongnu raids continued periodically in the subsequent period, but all references to the tribe disappear after the 5th century. The dominant nomad people in the Mongolian steppe in the 7th century, the Tujue, were identified with the Turks and claimed to be descended from the Xiongnu. A number of Xiongnu customs do suggest Turkish affinity, which has led some historians to suggest that the western Xiongnu may have been the ancestors of the European Turks of later centuries. Others believe that the Xiongnu are the Huns, who invaded the Roman Empire in the 5th century. Though possible, this view cannot be substantiated. The graves of several chanyu (Xiongnu chiefs) excavated in the Selenga River valley in southern Siberia have been found to contain remains of Chinese, Iranian, and Greek textiles, indicating a wide trade between the Xiongnu and distant peoples.