Second Letter of John of Monte Corvino (1305)

Writing from Khanbaliq, John of Monte Corvino relayed the culture and histories he observed in a series of letters sent to the Pope. In what is called his Second Letter,  John tells the story of a Nestorian King George, a relative of Prester John, which in structure matches the Prester John story found in Marco Polo and in most of the other mid-thirteenth century missionary travel narratives. 
 

From Dawson’s English translation (pp. 226-7):

A certain king of these parts, of the sect of the Nestorian Christians, who was of the family of that great king who was called Prester John of India, attached himself to me in the first year that I came here. And he was converted by me to the truth of the true Catholic faith. And he took minor orders and served my Mass wearing the sacred vestments, so that the other Nestorians accused him of apostasy. Nevertheless he brought a great part of his people to the true Catholic faith… This King George departed to the Lord a true Christian… But his brothers who were perverse in the errors of Nestorius perverted all those whom King George had converted…” 

Read John of Monte Corvino’s Report from China.