John, Prester, a supposed king and priest of a mediæval kingdom in the interior of Asia; converted to Christianity by the Nestorian missionaries; was defeated and killed in 1202 by Genghis Khan, who had been tributary to him but had revolted; he was distinguished for piety and magnificence.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
John, Knights of St. * John, St.