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
In 318, after suppressing a coup by a powerful minister in the Xiongnu-Han court, in which the emperor and a large proportion of the aristocracy were massacred), the Xiongnu prince Liu Yao moved the Xiongnu-Han capital from Pingyang to Chang'an and renamed the dynasty as Zhao (Liu Yuan had declared the empire's name Han to create a linkage with Han Dynasty—to which he claimed he was a descendant, through a princess, but Liu Yao felt that it was time to end the linkage with Han and explicitly restore the linkage to the great Xiongnu chanyu Maodun, and therefore decided to change the name of the state. (However, this was not a break from Liu Yuan, as he continued to honor Liu Yuan and Liu Cong posthumously; it is hence known to historians collectively as Han Zhao).