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.
Xubu
The Xubu () was a tribe of the Xiongnu confederation that flourished between 3rd century BCE to 4th century CE. Chinese annals noted that the Xubu tribe replaced the Huyan tribe, which was an earlier maternal dynastic tribe of the dynastic union with the paternal dynastic tribe Luandi. The traditional system of conjugal unions is a form of the nomadic exogamic society. The male members of the maternal dynastic line were not eligible for the Chanyu throne, only the male members of the Luandi line, whose father was a Luanti Chanyu, and mother was a Xubu Khatun (Queen) were eligible for the supreme throne. A Xubu could only become a Chanyu after a palace coup.