History of the Tartars
Historia Tartarum (c. 1246)
Most of Ascelin’s journey to the land of the Tartars is lost, but that which remains, recorded by Simon of Saint-Quentin, was kept alive by Vincent of Beauvais in his Speculum Historiale.
As Morgan (p. 164) relates, "Simon had evidently picked up the story of Toghril's defeat at the hands of Chinggis Khan, and his subsequent death. For him, though, Chinggis's defeated enemy remains King David, son of Prester John, king of India."
In the portion of the narrative that survives (that which was transcribed by Vincent of Beauvais), Ascelin also reports that Prester John has integrated his family into the Mongol royal family by betrothing Prester John’s granddaughter to Chinggis Khan.
For more on Simon’s text and journey, see Guzman and Brewer (pp. 155-159).
