Han dynasty
To the north of China proper, the nomadic Xiongnu chieftain Modu Chanyu (r. 209–174 BC) conquered various tribes inhabiting the eastern portion of the Eurasian Steppe. By the end of his reign, he controlled Manchuria, Mongolia, and the Tarim Basin, subjugating over twenty states east of Samarkand. Emperor Gaozu was troubled about the abundant Han-manufactured iron weapons traded to the Xiongnu along the northern borders, and he established a trade embargo against the group. In retaliation, the Xiongnu invaded what is now Shanxi province, where they defeated the Han forces at Baideng in 200 BC. After negotiations, the "heqin" agreement in 198 BC nominally held the leaders of the Xiongnu and the Han as equal partners in a royal marriage alliance, but the Han were forced to send large amounts of tribute items such as silk clothes, food, and wine to the Xiongnu.
Origin of the Huns
Other scholars have put forth evidence from non-European sources to support a link. Writing in third-century China, a Buddhist monk from northern Bactria (modern Afghanistan), named Zhu Fahu (in Chinese) or "Dharmarakṣa" (in Sanskrit), translated the ethnonym "Huṇa" from Sanskrit into Chinese as "Xiongnu". This is the earliest attested usage of the name Huṇa, and Étienne de la Vaissière argues that "the use of the name Huṇa in these texts has a precise political reference to the Xiongnu". A second important piece of textual evidence is the letter of a Sogdian merchant named Nanaivande, written in 313: the letter describes raids by the "Xwn" on cities in Northern China. Contemporary Chinese sources identify these same people as the Xiongnu. De la Vaissière, therefore, concludes that "'Hun/Xwm/Huṇa' were the exact transcriptions of the name that the Chinese [...] had rendered as 'Xiongnu'".
Another important historical document supporting the identification is the "Wei shu". Scholar Friedrich Hirth (1909) believed that a passage in the "Wei Shu" identified the Xiongnu as conquering the Alans and the Crimea, the first conquests of the European Huns. Otto Maenchen-Helfen was able to show that Hirth's identification of the people and land conquered as the Alans and the Crimea was untenable, however: the "Wei Shu" instead referred to a conquest of Sogdia by a group that Maenchen-Helfen identified with the Hephthalites, and much of the text was corrupted by later interpolations from other sources. De la Vaissière, however, notes that a Chinese encyclopedia known as the "Tongdian" preserves parts of the original "Wei Shu", including the passage discussed by Hirth and Maenchen-Helfen: he notes that it describes the conquest of Sogdia by the Xiongnu at around 367, the same time that Persian and Armenian sources describe the Persians fighting the Chionites. Sinor explicitly denied any connection between the Chionites and the Huns, claiming the former to have been Turks, unlike the Huns. However, writing in 2013, Hyun Jin Kim refers to a "general consensus among Historians that the Chionites and the Huns were one and the same". A fifth-century Chinese geographical work, the "Shi-san zhou ji" by Gan Yi, notes that the Alans and Sogdians were under different rulers (the European Huns and the Chionites respectively), suggesting some believed that they had been conquered by the same people.