South Hwanghae Province
Kim was born in Teot-gol (텃골), Baek-un-bang (백운방), Haeju, South Hwanghae Province, Korea, the only son of the farmers Kim Soon-young (김순영) and Kwak Nack-won (곽낙원). His name at birth was Kim Changahm (; ). When he was nine years old, he started to study Chinese classic texts such as "Zizhi Tongjian", and "Great Learning" at local seodangs.