that we are thus oppressed by our neighbours.’  So both Tartars and Moal made Chinghis himself their leader and captain.  And having got a host quietly together, he made a sudden onslaught upon Unc and conquered him, and compelled him to flee into Cathay.  On that occasion his daughter was taken, and given by Chinghis to one of his sons, to whom she bore Mangu, who now reigneth....  The land in which they (the Mongols) first were, and where the residence of Chinghis still exists, is called Onan Kerule.[11] But because Caracoran is in the country which was their first conquest, they regard it as a royal city, and there hold the elections of their Chan.”

Here we see plainly that the Unc Chan of Rubruquis is the Unc Can or Unecan of Polo.  In the narrative of the former, Unc is only connected with King or Prester John; in that of the latter, rehearsing the story as heard some 20 or 25 years later, the two are identified.  The shadowy role of Prester John has passed from the Ruler of Kara Khitai to the Chief of the Keraits.  This transfer brings us to another history.

We have already spoken of the extensive diffusion of Nestorian Christianity in Asia during the early and Middle Ages.  The Christian historian Gregory Abulfaraj relates a curious history of the conversion, in the beginning of the 11th century, of the King of Kerith with his people, dwelling in the remote north-east of the land of the Turks.  And that the Keraits continued to profess Christianity down to the time of Chinghiz is attested by Rashiduddin’s direct statement, as well as by the numerous Christian princesses from that tribe of whom we hear in Mongol history.  It is the chief of this tribe of whom Rubruquis and Polo speak under the name of Unc Khan, and whom the latter identifies with Prester John.  His proper name is called Tuli by the Chinese, and Togrul by the Persian historians, but the Kin sovereign of Northern China had conferred on him the title of Wang or King, from which his people gave him the slightly corrupted cognomen of [Arabic], which some scholars read Awang, and Avenk Khan, but which the spelling of Rubruquis and Polo shows probably to have been pronounced as Aung or Ung Khan.[12] The circumstance stated by Rubruquis of his having abandoned the profession of Christianity, is not alluded to by Eastern writers; but in any case his career is not a credit to the Faith.  I cannot find any satisfactory corroboration of the claims of supremacy over the Mongols which Polo ascribes to Aung Khan.  But that his power and dignity were considerable, appears from the term Padshah which Rashiduddin applies to him.  He had at first obtained the sovereignty of the Keraits by the murder of two of his brothers and several nephews.  Yessugai, the father of Chinghiz, had been his staunch friend, and had aided him effectually to recover his dominion from which he had been expelled.  After a reign