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.
Huns
Since Joseph de Guignes in the , modern historians have associated the Huns who appeared on the borders of Europe in the with the Xiongnu who had invaded China from the territory of present-day Mongolia between the and the . Due to the devastating defeat by the Chinese Han dynasty, the northern branch of the Xiongnu had retreated north-westward; their descendants may have migrated through Eurasia and consequently they may have some degree of cultural and genetic continuity with the Huns. Scholars also discussed the relationship between the Xungnu, the Huns, and a number of people in central Asia were also known as or came to be identified with the name "Hun" or "Iranian Huns", the Chionites, the Kidarites, and the Hephthalites (or White Huns) being the most prominent.