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.
Origin of the Huns
At the beginning of the twentiethcentury, German Sinologist Friedrich Hirth discovered passages in the Chinese annals that he believed proved the connection between the Huns and the Xiongnu. Hirth's work convinced many, and by the 1940s there was a general consensus among historians and archaeologists that the Xiongnu and the Huns were related. However, Otto J. Maenchen-Helfen showed conclusively that Hirth had misinterpreted the Chinese annals in 1945. Maenchen-Helfen also argued against the identification based on then-current archaeology and on ethnographic grounds. While he did not address the question in his most important work, "The World of the Huns" (1973), Maenchen-Helfen would go on to cast doubt on new theories that equated the Huns and the Xiongnu on the basis of their names in several articles. Maenchen-Helfen's skepticism was also taken up by prominent Eurasianist Denis Sinor.