Yi Ja-chun
Yi Ja-chun (20 January 1315 – 3 June 1361) or known by his Mongolian name Ulus Bukha (울루스부카, 吾魯思不花), was a minor military officer of the Yuan Empire who later transferred his allegiance to Goryeo and became the father of Yi Seonggye, founder of the Joseon Dynasty.

Biography
Yi Ja-chun was a mingghan (chief of one thousand) of the Yuan Dynasty in Ssangseong Prefectures (雙城; present-day Kŭmya County, South Hamgyŏng Province, North Korea - territory which was then administered by the Mongol Empire as part of the terms of the vassaldom of Goryeo to the empire). After Ssangseong was annexed by Goryeo under King Gongmin, he migrated to Hamju and got promoted to manho (the equivalent of the Mongolian tümen, lit. ten thousand or chief of ten thousand). He married a Goryeo-Korean lady from Anbyeon, who became Queen Uihye, the mother of Yi Seong-gye. He died in Hamgyong in 1361.

Since he was glamorized by his descendants, descriptions of Yi Ja-chun's life tend to be contradictory to each other. For example, he is said to have risen to the rank of scholar-official. However, when he died, the king at the time expressed condolences for Ja-chun as if for scholar-officials, implying that Yi Ja-chun was not a scholar-official.

Family
Father: Yi Chun (이춘, d. 1342)
Grandfather: Yi Haengni (이행리)
Grandmother: Queen Jeongsuk of the Yeongheung Choi clan (정숙왕후 최씨)
Mother: Queen Gyeongsun of the Munju Bak clan (경순왕후 박씨)
Grandfather: Bak Gwang (박광)
Wives and their Children:
Lady, of the Hansan Yi clan (부인 한산이씨; d. 1333)
Yi Won-gye, Grand Prince Wanpung (이원계 완풍대군; 1330–1388)
Yi Cheon-gye, Grand Prince Yeongseong (이천계 영성대군; 1333–1376)
Lady Yi (부인 이씨) – married Gang U (강우, 康祐)
Queen Uihye of the Yeongheung Choe clan (의혜왕후 최씨)
Yi Seong-gye, King Taejo of Joseon (이성계 조선 태조; 1335–1408)
Princess Jeonghwa (정화공주)
Lady Gim Goeumga (김고음가; d. 1404)
Yi Hwa, Grand Prince Uian (이화 의안대군; 1348–1408)
Unknown woman
Yi Yeong (이영; d. 1394)

In popular culture
Portrayed by Jeon Byung-ok in the 2005–2006 MBC TV series Shin Don.
Portrayed by Jung Dong-gyu in the 2012 SBS TV series Faith.
 Portrayed by Lee Soon-jae in the 2015–2016 SBS TV series Six Flying Dragons.

References

See also 
List of Goryeo people
History of Korea

14th-century Korean people
Korean generals
House of Yi
1315 births
1361 deaths
Yuan dynasty people
People from Kumya County