Baekje's Expansion to Mahan(馬韓) and the Forces Around Woongcheon(熊川) in the Late 3rd and the Early 4th Century

According to 『Samguksagi(三國史記)』, Baekje(百濟) was expanded to the Woongcheon area in the 13th year of King Onjo, and installed the Woongcheon-Chaek(柵) in the 24th year of his reign. Woongcheon is Anseong River. Baekje was expended to this place at the beginning of the reign of King Goi, and set up Woongcheon-Chaek in the latter period of his reign. Baekje acknowledged the superiority of Mokji(目支) State in order to cope with the threats of Malgal(靺鞨) and Lolang(樂浪) and to be recognized for its influence on the northern Woongcheon in the early days of King Koi. The weakened Mokji State maintained friendly relationships with Baekje to maintain its influence on the surrounding small state in the middle of the third century. Baekje tried to establish the domination of the northern Woongchon by installing Woongchon-Chaek in the north of Anseong River. It would have been placed in the west of Jinsari Castle, and in the east of where Anseong River meets Jinwi River. The forces around them accepted the existence of Woongchon-Chaek, but the forces of Anseong adhered to friendly relationships with the Mokji State. Baekje abolished the Chaek, but secured a substantial advantage over Mokji State. Baekje conquered around Mokji State in the late 3rd and the early 4th century. During this period, Baekje also took control of Woongcheon area. In this area, the existing castles of the small states turned into an autonomous castle and cooperated with Baekje's domination. Baekje set up strategic castle to control external defense and surrounding autonomous castles. Dogidong Castle was changed from autonomous castle to strategic one in the 4th century. This is because Anseong was located between Hanseong(漢城) and the upper and middle streams of Geum River. Because the Anseong forces cooperated with policy of Paekche, Dogidong Castle was strengthened as a strategic base. The above shows that a ruling system was formed and it organically connects the strategic castle and autonomous castle around of Woongcheon in the 4th century.