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.
Five Barbarians
Liaison among the dynasty and groups of herdsmen relied on mutual economic and military benefits. As the Northern Xiongnu, the masters of the Mongolian steppes and mortal enemy of the Han dynasty, were still potent enough during the reigns of Emperor Ming, Emperor Zhang and Emperor He (58–105) to keep the volatile alliance intact, the Eastern Han dynasty enjoyed the most prosperous years of its almost 200 years of existence. Even fragments of the Northern Xiongnu migrated well within the border to the Xihe plain, west of the Yellow River and south of the Ordos Desert).