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.
Origin of the Huns
The chief piece of evidence linking the Xiongnu to the European and Iranian Huns is the similarity of their names. Supporting evidence is provided by historical records indicating that the term "Xiongnu" was used for the people referred to in Sogdian and Sanskrit texts as the "Xwn" and "Huṇa" respectively, terms used for peoples called Huns in the West. Another important connection is the use of similar metallic cauldrons by the European Huns and the Xiongnu. There remain a number of outstanding differences, however, including generally different archaeological profiles and a wide variety of customs attested among the various Hunnic groups. Additionally, there is a two hundred year gap between the last recorded activities of the Xiongnu and the first appearance of the Huns in Europe and Central Asia. These issues have caused some scholars to reject the identification.