returned home. And Chinghis addressed the Tartars and Moal, saying: 'It is
because we have no leader 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