Xiongnu
The Xiongnu () were a confederation of nomadic peoples who, according to ancient Chinese sources, inhabited the eastern Asian Steppe from the 3rd century BC to the late 1st century AD. Chinese sources report that Modu Chanyu, the supreme leader after 209 BC, founded the Xiongnu Empire.
Emperor Wen of Han
In 169 BC, Chao Cuo (晁錯), then a low-level official, offered Emperor Wen a number of suggestions for dealing with the Xiongnu. Emperor Wen was impressed, and made him a member of Crown Prince Qi's household. At Chao's suggestion, in 168 BC, Emperor Wen instituted the policy that if people contributed food for use by the northern defense force against Xiongnu, they could receive titles or have their crimes pardoned.