Paekche, one of three kingdoms into which ancient Korea was divided before 660. Occupying the southwestern tip of the Korean peninsula, Paekche is traditionally said to have been founded in 18 bc in the Kwangju area by a legendary leader named Onjo. By the 3rd century ad, during the reign of King Koi (234–286), Paekche emerged as a fully developed kingdom. By the reign of King Kŭnch’ogo (346–375), it had established control over a region that included the whole Han River basin in central Korea.