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.
Xianyun
Later Chinese annals contain a number of references to the Xianyun, such as by Sima Qian (c. 145/135 – 86 BCE), Ying Shao (140-206 CE), Wei Zhao (204-273 CE), and Jin Zhuo (late 3rd–4th century CE). Without giving specific arguments, they stated that Xunyu (獯鬻) or "Xianyun" were terms that designated nomadic people who later during the Han dynasty were transcribed as "Xiongnu" (匈奴). This view was also held by the Tang dynasty commentator Sima Zhen (c. 8th century CE). Wang Guowei (1877–1927), as a result of phonetical studies and comparisons based on the inscriptions on bronze and the structure of the characters, came to the conclusion that the tribal names "Guifang" (鬼方), "Xunyu" (獯鬻), "Xianyu" (鮮虞), Xianyun, "Rong" (戎), "Di" (狄), and "Hu" (胡) given in the annals designated one and the same people, who later entered history under the name Xiongnu.