Where exactly the legend began is unsure. There was a Prester John in the very early years of the Christian church in the area of Syria, but little is known of this shadowy figure and he was by no means a king or great priest. I feel, as do many that the legend really took hold because there was a desire for the Christian west to not feel so isolated in its fight against first the Islamic Turks and Arabs and then later against the Mongols (mix of pagan, Buddhist, and later Muslim). The New Testament contains several stories of the early Christian missionaries heading far to the east in search of converting people in Persia and even as far as India. St. Thomas especially is recorded as venturing far off to the east to spread the new religion of Jesus.
Between the first and second crusades there were rumors that there were archbishops, patriarchs, and other emissaries of a Christain king of the far east named Prester John visiting Rome as well as the Byzantines in Constantinople. The rumors varied but most stated that just like the infant crusader states in the holy land, the kingdom in the east was fighting for survival against the Muslims as well. Some details about Prester John started to emerge. The general consensus that he was a decendent of one of the three magi that had visited the infant Jesus at his birth and that he was not only king but head of Christianity in his land. The brand of Christianity was also rumored to not be of the Byzantine or Roman church, but that the "Christians of St. Thomas" practiced Nestorian Christianity which treated the divinity of Jesus differently than the churches of the west. Nestorianism had indeed split with the Byzantine many years previously and followers did end up fleeing to Persia and establishing small Christian communities in the area. It was rumored that this lost Christian kingdom lay somewhere near Persia and India so the Nestorian connection made sense to many, including church leaders in Constantinople and Rome.
Around the time of the second crusade when fortunes for the Crusader states started to turn from victory to uneasy stalemate there was talk that Prester John had embarked on a crusade of his own and had marched through Persia and had intended to march toward Jerusalem to join his western comrades, but could not cross the flooded Tigris river in Mesopotamia and was forced to return home. Indeed there had been a new army in Persia at the time that had indeed defeated the Sejuk Turks in the area, but it was no Christian force, it was instead an army of Buddhist Mongols. Then for almost 20 years there was little new on the rumored monarch...until a letter arrived for the Byzantine emperor in 1165.
The Prester John letter, a hoax most likely perpetrated by a westerner took Europe by storm and was translated into many languages. It detailed the vast richness of the kingdom and assured the monarch that there was another Christian force in the world fighting the "infidels". The Pope in Rome drafted a letter to the mysterious king and sent an emissary to hand deliver it. Both the letter and the emissary where never seen again after leaving Christian lands. Again all fell silent until the return of new rumors following the disaster that was the Firth Crusade to Egypt (1215-1221). Rumors returned that Prester John's heir, named David, was conquering from the east. Again it was disappointing to the kings and ecclesiastical leaders of Europe when the rumors proved false, and the new conquering force was actually the pagan Genghis Khan.
After the conquest of Genghis Khan the legend of Prester John changed from a great and powerful monarch to just one of many weaker adversaries swallowed up by the tide of the more powerful Mongol hordes. However, for many centuries western scholars eager to put some validity to the rumors tried to make the idea of Prester John fit in somewhere with the smaller Christian rulers of the Caucus Mountains and even later in Ethiopia. No one really knows how such a rumor got started, but the legend of Prester John is one of the most interesting and long lived rumors/legends of the medieval and Renaissance Christian world.
|Rendering of Prester John from the later period of the myth that attempted to place his kingdom in Africa|