The link between Prester John and Genghis Khan was elaborated upon at this time, as the Prester became identified with Genghis' foster father, Toghrul, king of the Keraites, given the Jin title Ong Khan Toghrul. Fairly truthful chroniclers and explorers such as Marco Polo, Crusader-historian Jean de Joinville, and the Franciscan voyager Odoric of Pordenone stripped Prester John of much of his otherworldly veneer, portraying him as a more realistic earthly monarch. Odoric places John's land to the west of Cathay en route to Europe, and mentions its capital as Casan, which may correspond to Kazan, the Tatar capital near Moscow. Joinville describes Genghis Khan in his chronicle as a "wise man" who unites all the Tartar tribes and leads them to victory against their strongest enemy, Prester John. William of Rubruck says a certain "Vut", lord of the Keraites and brother to the Nestorian "King" John, was defeated by the Mongols under Genghis Khan. Genghis Khan made off with Vut's daughter and married her to his son, and their union produced Möngke, the Khan at the time William wrote. According to Marco Polo's "Travels", the war between the Prester and Genghis Khan started when Genghis Khan, new ruler of the rebellious Tartars, asked for the hand of Prester John's daughter in marriage. Angered that his lowly vassal would make such a request, Prester John denied him in no uncertain terms. In the war that followed, Genghis Khan triumphed, and Prester John perished.