Onjo settled in Wiryeseong (present-day Seoul), and called his country Sipje (meaning "Ten Vassals"), while Biryu settle in Michuhol (present-day Incheon), against the vassals' advice. The salty water and marshes in Michuhol made settlement difficult, while the people of Wiryeseong lived prosperously. In shame, Biryu committed suicide, and his people moved to Wiryeseong, where King Onjo welcomed them and renamed his country Baekje ("Hundred Vassals").
King Onjo moved the capital from the south to the north of the Han River, and then south again, probably all within present Seoul, under pressure from other Mahan states. Evidence suggests that King Gaeru moved the capital to the Bukhan Mountain Fortress in 132 C.E., probably in present-day Gwangju City (Gyeonggi), to the southeast of Seoul. Through the early centuries of the Common Era, sometimes called the Proto-Three Kingdoms Period, Baekje gradually gained control over the other Mahan tribes