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.
Xiongnu
Since the early 19th century, a number of Western scholars have proposed a connection between various language families or subfamilies and the language or languages of the Xiongnu. Albert Terrien de Lacouperie considered them to be multi-component groups. Many scholars believe the Xiongnu confederation was a mixture of different ethno-linguistic groups, and that their main language (as represented in the Chinese sources) and its relationships have not yet been satisfactorily determined. Kim rejects "old racial theories or even ethnic affiliations" in favour of the "historical reality of these extensive, multiethnic, polyglot steppe empires".