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
The supposed Old Chinese sound of the first character (匈) has a possible similarity with the name "Hun" in European languages. The second character (奴) appears to have no parallel in Western terminology. Whether the similarity is evidence of kinship or mere coincidence is hard to tell. It could lend credence to the theory that the Huns were in fact descendants of the Northern Xiongnu who migrated westward, or that the Huns were using a name borrowed from the Northern Xiongnu, or that these Xiongnu made up part of the Hun confederation.