The Battle of Guandu was fought between the warlords Cao Cao and Yuan Shao in 200 CE in the late Eastern Han dynasty. The battle, which concluded with a decisive victory for Cao Cao, was a turning point in the war between the two warlords. It marked the beginning of Cao Cao's gradual reunification of northern China, which made possible the establishment of the state of Cao Wei in the Three Kingdoms period.