I should mention that Oppert, in his very interesting monograph, Der Presbyter Johannes, refuses to recognise the Kerait chief at all in that character, and supposes Polo’s King George to be the representative of a prince of the Liao (supra, p. 205), who, as we learn from De Mailla’s History, after the defeat of the Kin, in which he had assisted Chinghiz, settled in Liaotung, and received from the conqueror the title of King of the Liao.  This seems to me geographically and otherwise quite inadmissible.

[2] The term Arkaiun, or Arkaun, in this sense, occurs in the Armenian
    History of Stephen Orpelian, quoted by St. Martin.  The author of the
    Tarikh Jahan Kushai, cited by D’Ohsson, says that Christians were
    called by the Mongols Arkaun.  When Hulaku invested Baghdad we are
    told that he sent a letter to the Judges, Shaikhs, Doctors and
    Arkauns, promising to spare such as should act peaceably.  And in the
    subsequent sack we hear that no houses were spared except those of a
    few Arkauns and foreigners.  In Rashiduddin’s account of the Council
    of State at Peking, we are told that the four Fanchan, or Ministers
    of the Second Class, were taken from the four nations of Tajiks,
    Cathayans, Uighurs, and Arkaun.  Sabadin Arkaun was the name of one
    of the Envoys sent by Arghun Khan of Persia to the Pope in 1288. 
    Traces of the name appear also in Chinese documents of the Mongol era,
    as denoting some religious body.  Some of these have been quoted by
    Mr. Wylie; but I have seen no notice taken of a very curious extract
    given by Visdelou.  This states that Kublai in 1289 established a Board
    of nineteen chief officers to have surveillance of the affairs of the
    Religion of the Cross, of the Marha, the Siliepan, and the
    Yelikhawen.  This Board was raised to a higher rank in 1315:  and at
    that time 72 minor courts presiding over the religion of the
    Yelikhawen existed under its supervision.  Here we evidently have the
    word Arkhaiun in a Chinese form; and we may hazard the suggestion
    that Marha, Siliepan and Yelikhawen meant respectively the
    Armenian, Syrian, or Jacobite, and Nestorian Churches. (St. Martin,
    Mem. II. 133, 143, 279; D’Ohsson, II. 264; Ilchan, I. 150, 152;
    Cathay, 264; Acad. VII. 359; Wylie in J.  As. V. xix. 406.  Suppt.
    to D’Herbelot, 142.)

[3] The word is not in Zenker or Pavet de Courteille.

[4] Mr. Shaw writes Toonganee.  The first mention of this name that I
    know of is in Izzat Ullah’s Journal. (Vide J.  R. A. S. VII. 310.)
    The people are there said to have got the name from having first
    settled in Tungan.  Tung-gan is in the same page the name given to
    the strong city of T’ung Kwan on the Hwang-ho. (See Bk.  II. ch. xli.
    note 1.) A variety of etymologies have been given, but Vambery’s seems
    the most probable.