Ancient Korea - Before the Three Kingdoms period, the Korean peninsula had several states of which Kojoson was established first.
Image of the Tomb of King Tangun
Kojoson is the first Korean kingdom and was founded in 2333 BC. The Kosojon are the first direct Korean ancestral line recorded in writing.
It is thought that Kojoson was initially located in Liaoning (Northeast China), but that its capital eventually moved to Pyongyang at around 400 BC. Kojoson fell around 300 BC being divided into several smaller states.
Other slave-owning kingdoms that emerged were Puyo (7th century BC, covering a large area of the Songhwa River basin and the Liao River), Chinguk (south of the central area of the Korean peninsula, before the 6th century BC) and Kuryo (around the 5th century BC).
Various states would then exist until the Three Kingdoms era.