Baekje-Silla relationship was peaceful for most of his period of reign. In 165, Gilseon (길선/吉宣), a minister of Silla, failed his coup d'etat attempt and fled to Baekje. King Gaeru gave him refuge and the two countries became hostile.
According to Samguk Yusa, King Onjo was the son of Jumong (King Dongmyeongseong), the founder of Goguryeo.
KingGaeru is believed to have moved the capital to the Bukhan Mountain Fortress in 132, probably in present-day Gwangju, to the southeast of Seoul.
King Seong, for example, strengthened royal power, but after he was slain in a disastrous campaign against Silla, the nobles took much of that power away from his son.