Following the loosening of central government control due to the repercussions of the Yellow Turban Rebellion, bandits and rebels sprung up everywhere.
In 185, Zhang Niujue and fellow bandit Chu Yan (褚燕) joined forces to raid the town of Yingtao (癭陶).
While Zhu Jun was able to push them away from the capital,[2] the Han were unable to control the situation north of the Yellow River, the government accepted a nominal surrender and offered the bandits official positions.
Later, the Heishan bandits under Yu Du (于毒), joined by local rebels, stormed Yuan Shao's Ye city, capital of Wei Commandery (魏郡), and killed its Grand Administrator (太守) Li Cheng (栗成).
[6] Yuan Shao's campaign might have diminished the Heishan bandits' prospects in the south, but Zhang Yan and his people continued to hold out in the northern Changshan Commandery.