Noin-Ula burial site
Many immigrants lived in the Xiongnu pasturelands, but at first they did not mix with the Xiongnu. To be a Xiongnu, one had to be a member of a clan, born of Xiongnu parents. The newcomers were well off, but were outsiders, and could marry only among themselves, not the Xiongnu. Only later did they intermix, increase in numbers, even created a state that existed from 318 to 350 AD.
Xiongnu
In the winter of 200 BC, following a siege of Taiyuan, Emperor Gaozu of Han personally led a military campaign against Modun. At the Battle of Baideng, he was ambushed reputedly by 300,000 elite Xiongnu cavalry. The emperor was cut off from supplies and reinforcements for seven days, only narrowly escaping capture.