Ordos Plateau
In Chinese accounts, the Xiongnu first appear at Ordos in the "Yizhoushu" and "Shanhaijing" during the Warring States period before it was occupied by Qin and Zhao. It is generally thought to be their homeland, however when exactly they came to occupy the region is unclear, and it might have been much earlier than traditionally thought, as suggested by archaeological finds. As the Xiongnu expanded southward into Yuezhi territory around 160 BC under their leader Modun, the Yuezhi in turn defeated the Sakas (Scythians) and pushed them away at the Issyk Kul. It is thought the Xiongnu also occupied the Ordos area during the same period, when they came in direct contact with the Chinese. From there, the Xiongnu conducted numerous devastating raids into Chinese territory (167, 158, 142, 129 BC). The Han Dynasty started to fight the Xiongnu in the 2nd century BC under emperor Han Wudi, and colonized the area of the Ordos under Shuofang commandery in 127 BC. Prior to the campaign, there were already commanderies established earlier by Qin and Zhao until they were overrun by the Xiongnu in 209 BC.
Mongols
After the Donghu were defeated by Xiongnu king Modu Chanyu, the Xianbei and Wuhuan survived as the main remnants of the confederation. Tadun Khan of the Wuhuan (died 207 AD) was the ancestor of the proto-Mongolic Kumo Xi. The Wuhuan are of the direct Donghu royal line and the "New Book of Tang" says that in 209 BCE, Modu Chanyu defeated the Wuhuan instead of using the word Donghu. The Xianbei, however, were of the lateral Donghu line and had a somewhat separate identity, although they shared the same language with the Wuhuan. In 49 CE the Xianbei ruler Bianhe (Bayan Khan?) raided and defeated the Xiongnu, killing 2000, after having received generous gifts from Emperor Guangwu of Han. The Xianbei reached their peak under Tanshihuai Khan (reigned 156–181) who expanded the vast, but short lived, Xianbei state (93–234).