Yesugei Baghatur or Yesugei The Brave (11XX–1180) (Yesügei, Yesükhei) was a Mongol Khan (or ruler). He was chief of the Qiyat (possibly the Taichiut or Yakka) khanate between approximately 1153 and 1180. He had four sons and one daughter by his chief wife, Oyelun: Temujin (son), Kasar (son), Khaji'un (son), Temuga (son), and Temulin (daughter). He also had two sons by a lesser wife: Bektor and Beigutai . He was poisoned by tartars while sharing a meal on the way home from finding his son Temujin, Genghis Khan, a wife. He was the son of Bartan -baghatur, who was the son of Qabul Khagan, who was recognized as a Khagan by the Qin Dynasty. Qabul Khagan was, in turn, the grandson of the mongol chief Qaidu , the first to try to unite all of the Mongols.

Yesugei's was Oyelun (Oelun, Ho’elun, Hoelun), a daughter of the Olkunut forest tribe. Oyelun was abducted by Yesugei and his brothers from her newlywed husband of the Merkit tribe as they were traveling back to the Merkit camp. Yesugei then made Oyelun his chief wife, a rare honor since Khan’s had several wives, and only one could bear his heirs.