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.
Turkic migration
The population ancestral to the Turks is thought to have included the Xiongnu of Mongolia or along the upper Yenisei in Siberia (the area of the contemporary Tuvan language), known from historical sources. The Han chronicle of the Xiongnu, included in the "Records of the Grand Historian" of the second century BCE, traces a legendary history of them back a thousand years before the Han to a legendary ancestor, Chunwei, a supposed descendant of the Chinese rulers of the Xia dynasty (c. 2070 – c. 1600 BCE). Chunwei lived among the "Mountain Barbarians" Xianyun or Hunzhu. Xianyun and Hunzhu's names may connect them to the Turkic people, who later were said to have been iron-workers and to have kept a national shrine in a mountain cave in Mongolia.