At the beginning of the Han Dynasty, Liu Bang had made many of his relatives kings of certain sections, about two-thirds, of the empire. This was an attempt to consolidate Liu family rule over the parts of China that were not ruled directly from the capital under the junxian commandery system.
During the reign of Emperor Wen (Han WenDi), these kings began to set their own laws, cast their own coins, collect their own taxes and publicly oppose the central government. When Emperor Jing (Han JingDi) came to power in 157 BC, the rich kingdom of Wu was especially domineering. In response, Jingdi attempted to curtail the power of these kings, but in 154 BC, the king of Wu persuaded the kings of all of the seven kingdoms to a revolt against the central government. Jingdi ordered Zhou Yafu to launch an attack against the revolting army and put down the revolt in a three month campaign. After the rebellion had been crushed, Han Jingdi was free to weaken the power of these kings and expand the junxian system over more territory.