According to medievalrelating to the Middle Ages in Europe, a period from about A.D. 500 to 1500 legend, Prester John was a Christian king who ruled over an Asian land. The story of Prester John started around the time of the Crusades, the military campaigns undertaken by European Christians to retake the Holy Land from the Muslims.

A report written in 1145 called Prester John a mighty priest and king, who defeated the Persian Muslims and planned to help the Crusaders free Jerusalem. Twenty years later, a letter supposedly written by Prester John circulated in Europe. In it, he described his kingdom as a paradise on earth. He also promised to defeat the Muslims and recapture Christian holy places.

In 1177 Pope Alexander III sent a group to locate Prester John, but they were unsuccessful. Over the next few hundred years, many explorers and missionaries searched...