In 1202 the tribe of the Karaites became the vassals of the great conqueror Ghenghiz Khan, who is said to have added to his wives the Christian daughter of the last Ung-Khan of the tribe.
Thence he made his way over a roughly paved stone causeway one of those roads that the Chinese proverb says is "good for ten years and bad for ten thousand" between endless fields of high millet to the biggest gate of Peking itself. To step through the gate was to step back into the Middle Ages into the times of Ghenghiz Khan.
The kingdom of Prester John, however, lived on in fables, of which the best known relates how the Holy Grail, the cup consecrated by Christ at the Last Supper, had withdrawn from the sinful West and found refuge in this distant land. The conquests of Ghenghiz opened an entirely new chapter in the relations between Western Europe and the Mongols.
From the Khan of Kipchak at the Golden Horde on the Volga they were passed on to the Great Khan, who ruled now from the old capital of the Karaites at Karakorum. Here they were received in friendly fashion by the newly elected Kuyuk, grandson of Ghenghiz.
Ghenghiz himself before his death in 1227 overran China, Central Asia, Persia, and penetrated as far west as the Dnieper.