The historical figure behind these accounts, Toghrul, was in fact a Nestorian Christian monarch defeated by Genghis Khan. He had fostered the future Khan after the death of his father Yesugei and was one of his early allies, but the two had a falling-out. After Toghrul rejected a proposal to wed his son and daughter to Genghis Khan's children, the rift between them grew until war broke out in 1203. Genghis Khan captured Sorghaghtani Beki, daughter of Toghrul's brother Jaqa Gambu, and married her to his son Tolui; they had several children, including Möngke, Kublai, Hulagu, and Ariq Böke.