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.
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.