Wang Khan; also Ong Khan; was the title given to the Kerait ruler Toghrul by the Jurchen Jin Dynasty of China. Like the rest of their tribe he may have been Nestorian Christian. Wang Khan was the blood-brother of Temujin's (later Genghis Khan) father Yesukhei; and acted as a patron and early ally for Temujin. Genghis married his son Tolui to one of Toghrul's nieces; the Nestorian Christian Sorghaghtani Beki. Tolui and Sorghaghtani Beki became the parents of Mongke Khan and Kublai Khan. During the 13th century; Wang Khan was one of several Asian or African leaders who was identified with the legend of Prester John.