Legendary character, priest and monarch of the Christian East. It appears in the historical traditions of the middle ages and is protagonist in many medieval narratives. The geographical location of his Kingdom has always remained undetermined, and places it between Asia and Africa. This confusion is due to the ambiguous meaning of the denominations of India and Ethiopia in medieval geography. Proof of his existence and his zeal for Christianity was based, for a long time on the testimony given by a Syrian Bishop who visited Rome in 1145, and in a letter to the Emperor of Constantinople, to 1165, was signed with that name.
Currently, different indications, suggest that pay Juan was a monarch of character religious, Christian, but alien to Catholicism, who ruled the East of Persia, between the Caucasus and China. The location of their strengths enabled him to control the land routes of the silk and the trade between the Mediterranean and China. Erroneously the name of land of pay Juan had been to the enclaves of Coptic Christians in the Sudan, Ethiopia, and part of the South of Egypt, who survived the Muslim expansion covered in the freedom of worship which the Islamic Caliphs allowed.