There was a tradition that the Central Asian Naimans and their Christian relatives, the Keraites, were descended from the biblical Magi. This heritage passed to the Mongol dynasty of Genghis Khan when Sorghaghtani, niece of the Keraite ruler Toghrul, married Tolui, the youngest son of Genghis, and became the mother of Möngke Khan and his younger brother and successor, Kublai Khan. Toghrul became identified with the legendary Central Asian Christian king Prester John, whose Mongol descendants were sought as allies against the Muslims by contemporary European monarchs and popes. Sempad the Constable, elder brother of King Hetoum I of Cilician Armenia, visited the Mongol court in Karakorum in 1247–1250 and in 1254. He wrote a letter to Henry I King of Cyprus and Queen Stephanie (Sempad's sister) from Samarkand in 1243, in which he said: "Tanchat [Tangut, or Western Xia, which is the land from whence came the Three Kings to Bethlehem to worship the Lord Jesus which was born. And know that the power of Christ has been, and is, so great, that the people of that land are Christians; and the whole land of Chata or Kara-Khitai believes those Three Kings. I have myself been in their churches and have seen pictures of Jesus Christ and the Three Kings, one offering gold, the second frankincense, and the third myrrh. And it is through those Three Kings that they believe in Christ, and that the Chan and his people have now become Christians. The legendary Christian ruler of Central Asia Prester John was reportedly a descendant of one of the Magi.