Three Kingdoms - Koguryo, Paekche and Silla ( 57 bce–668 ce)

 In the first centuries AD, three kingdoms emerged on the Korean peninsula and the East-North of modern China as a result of unification of tribes that had populated the area. The legend from the Korean annals "Samguk sagi" (Historic chronicles of the Three Kingdoms) says that Koguryo (高句麗) was established by Jumon (Chumo) from the land of Northern Puyo. It occupied vast areas from Kaesong to the North.  

Chinese records Sanguozhi noted that "by the old Puyo tradition, in case of drouth, bad harvest of crops, the the blame fell on the King who was given a choice - to vale a crown or to commit suicide". 

The emerging of Koguryo was followed by endless wars with Chinese neighbors. Kings frequently changed one another, as the most cruel of them were assassinated. By 4th century, Confucianism from China became the main ideology in the country, and the state religion Buddhism had replaced and partly absorbed animistic and tribal beliefs.  

Paekche (百濟) was situated on the South-West end of Korean peninsula, having emerged on the basis of local tribal unions. As some historians claimed, it could happen in the last centuries BC. According to old legends, the founder of Paekche was a Onjo, son of Koguryo's founder Jumon. It could be a sign of ethnical similarity of Koguryo and Paekche as well as the fact that peoples in both states worshiped their common ancestor Tongmyon. But it didn't mean that their coexistence was peaceful. In 371 AD after attack from Koguryo, Paekche with 30 thousand men army surrounded Pyongyang and killed the Koguryo King Kogugwon. However they could not take over the capital city. Two decades later Koguryo's King Kwanggaeto ("Expanding territories") attacked Paekche and occupied its ten border fortresses. 

Silla (新羅) occupied a territory to the East of Paekche and to the West and South of Koguryo. As chronicles stated, Silla was founded in 57 BC by a person named Pak Hyokkose, who was elected to be the King. Situation inside the country was unstable until it established relations with Paekche and Koguryo. In 512 AD Silla conquered Ulleungdo Island, where a state called Usan had been reportedly situated. Later, together with Paekche, Silla confronted expansion of Koguryo to the south direction and successfully defeated a small tribal union of Kaya, that was the last stronghold of Japan on the Korean peninsula.