Yi Sng-gye (1335-1408) was the founder of the Yi dynasty, which lasted until 1910. An able military leader, he unified Korea under Chinese suzerainty.

Yi Sng-gye was born in modern Ynghung, the second son of Yi Chach'un. Yi's family, originally said to be of Chnju in the south, moved to the northeast in the second half of the 13th century. This migration was undertaken by Yi's great-great-grandfather, who later held a Mongol office. Yi's father is mentioned in the official annals for the first time in 1355, when he arrived in the capital to pay homage to King Kongmin. Later, when the King initiated a campaign to free himself from the Mongol occupation and to regain Korean territories in the north, Yi Chach'un received royal orders and participated in the successful campaign.

Thus Yi Sng-gye's ancestors were Kory nationals who had served the Mongols in the northeast. Because of geographical...