Nomadic empire
The Xiongnu were a confederation of nomadic tribes from Central Asia with a ruling class of unknown origin and other subjugated tribes. They lived on the Mongolian Plateau between the 3rd century BC and the 460s AD, their territories including modern day Mongolia, southern Siberia, western Manchuria, and the modern Chinese provinces of Inner Mongolia, Gansu, and Xinjiang. The Xiongnu was the first unified empire of nomadic peoples. Relations between early Chinese dynasties and the Xiongnu were complicated and included military conflict, exchanges of tribute and trade, and marriage treaties. When Emperor Qin Shihuang drove them away from the south of the Yellow River, he built the famous Great Wall to prevent the Xiongnu from coming back.
Donghu people
The (ca. 109–91 BCE) "Shiji" section on Xiongnu history first records the Donghu during the era of Duke Wen of Jin (r. 697–628 BCE) and Duke Mu of Qin (r. ca. 659–621 BCE).At this time Qin and Jin were the most powerful states in China. Duke Wen of Jin expelled the Di barbarians and drove them into the region west of the Yellow River between the Yun and Luo rivers; there they were known as the Red Di and the White Di. Shortly afterwards, Duke Mu of Qin, having obtained the services of You Yu, succeeded in getting the eight barbarian tribes of the west to submit to his authority.
Thus at this time there lived in the region west of Long the Mianzhu, the Hunrong, and the Diyuan tribes. North of Mts. Qi and Liang and the Jing and Qi rivers lived the Yiqu, Dali, Wuzhi, and Quyuan tribes. North of Jin were the Linhu (Forest Barbarians) and the Loufan, while north of Yan lived the Donghu (Eastern Barbarians) and Shanrong (Mountain Barbarians), each of them with their own chieftains. From time to time they would have gatherings of a hundred or so men, but no one tribe was capable of unifying the others under a single rule.