He was a member of the aristocratic Seok clan, which held the throne for much of the early period of Silla. According to the Samguk Sagi, he was the son of the general Uro, who was the son of Naehae Isageum. Although we do not know his year of birth, he was young when he first came to the throne.
The Samguk Sagi also relates an alliance by marriage with Wa, which was concluded in 313 but broke down in 346. In 347 there was a major invasion and the Japanese forces laid siege to Gyeongju.