Yi Ja-chun

Yi Jachun
Hangul
Hanja
Revised Romanization	I Ja-chun
McCune–Reischauer	I Cha-ch'un

Yi Ja-chun (Mongolian name: Ulus Bukha 吾魯思不花; 1315 – 1360) was a minor military officer of the Yuan Dynasty (he later transferred allegiance to the Goryeo Dynasty) and the father of Yi Seong-gye, the founder of the Joseon Dynasty. He was given the temple name Hwanjo (환조; 桓祖) by Taejong.

Yi Ja-chun was a mingghan (chief of one thousand) of the Yuan Dynasty in Ssangseong Prefectures (雙城;　Ssangseong in Korean, now Yŏnghŭng, Hamgyŏngnamdo, North Korea - territory which was then administered by the Mongol Empire as part of the terms of the vassaldom of Goryeo to that empire), but his ethnicity was Korean. After Shuangcheng was annexed by Goryeo under King Gongmin, he migrated to Hamju, Hamgyŏngnamdo and got promoted to manho (the equivalent of the Mongolian tümen, lit. ten thousand or chief of ten thousand). He died there in 1360.

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 Jachun as if for scholar-officials, implying that Yi Ja-chun was not a scholar-official.

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