m every sixth year.

[Sidenote: Prester John and his conversion.]

By the Middle Ages the Church of the East had spread over the whole of
Central Asia. The curious legends of the powerful kingdom of Prester
John, somewhere in the heart of Asia, grew out of the conversion, by
Nestorian merchants in the eleventh century, of a certain King of
Kerait, a kingdom of Tartary to the north of China. This king is said
to have requested that missionaries might be sent to him from the
Church {97} of his converters; and, when they were come, these
missionaries baptized him, naming him John,[7] and he was ordained
priest (Presbyter or Prester). Two hundred thousand people of the
nation embraced Christianity; the successors to the kingdom bore the
dynastic name of John, and were ordained priests. However uncertain
this story is, the fact of the conversion of the princes of Kerait in
Tartary is sufficiently well established. [Sidenote: Height of
prosperity.] The prosperity of the Church of the East culminated in the
eleventh century. The khalifs of Baghdad protected their Christian
subjects, and important offices of state were often filled by them.

The Indian Church, which was believed to date back to the time of S.
Thomas the Apostle, had probably its origin in Nestorian missions, and
accepted Monophysite opinions.

[Sidenote: Their missions]

As we have seen, the wider field of missionary work owed much to the
labours of the Nestorians. It is possible that Cosmas,[8] who had
travelled far afield in the first half of the sixth century, may have
been a Nestorian; but the reverence with which he speaks of the
orthodox faith, and his constant use of the Catholic writers, would
seem to show rather that, when he became a monk at any rate, he was
orthodox. From him, however, we obtain knowledge of the wide field of
Nestorian missions. Recent discoveries have largely added to our
knowledge. It is clear that in the sixth century, {98} apparently
before 540, Nestorian bishoprics were founded in Herat and Samarkand.
Monumental inscriptions date back as far as 547. [Sidenote: in the Far
East.] Merv, as early as 650, is spoken of as a "falling church" [9]
amid the triumphs of Islam. China has been already mentioned, and
though it is not clear that only Nestorian missions prospered in the
far land, there is no doubt that their success was the most prominent.
Christian communities existed near the borders of Tibet[10] in the
seve