Benjamin of Tudela… traveled in the East between the years of 1159-1173, the last being the date of his death. He wrote an account of his travels, and gives in it some information with regard to a mythical Jew king, who reigned in the utmost splendour over a realm inhabited by Jews alone, situate somewhere in the midst of a desert of vast extent.” 

The third interpolation [of the Letter of Prester John] has Prester John declare that each year he goes into the desert to pay homage to the tomb of Daniel, a figure of some mystical significance with a considerable apocryphal literature of his own. In the late twelfth century the Jewish traveler Benjamin of Tudela had been shown a tomb said to be Danel’s while he was in the Persian city of Susa, and this, possibly, led to the linking of Daniel and Prester John.

In our recollection, there were in Italy certain churches of the Christian Ethiopians, who they call Abassins or Abissins...  Indeed, by the navigations of the Portuguese, and by the splendid book of the journey of the Portuguese priest Francisco Alvarez, who penetrated into the inmost Ethiopia, one may learn many things about those men and their rites. Once, all Africa from the Nile's final mouth, to the Gaditan straits [i.e. the Straits of Gibraltar], and likewise from the Tyrrhenian Sea to beyond the Equinox towards the south, was full of Christian churches and cities, and this great tract of lands was obedient to the one Bishop of Alexandria. But if there are any churches remaining today in those parts, they recognise that patriarch alone, like these Ethiopians, being discussed now, and whom the lonely deserts and difficult routes defend from the general wasteland of Africa... Before the arrival of the Portuguese in Ethiopia, the name of the Ethiopian Christians alone was scarcely known to us, and their falsely named emperor Prestegiani; since that name does not belong to he who reigned in Ethiopia, but he who reigned in Asia three hundred years previously, a long way distant... they falsely call him Prestegiani, and [to say] that this Ethiopian is the same as that Asian man out of the itinerary of Paul the Venetian [i.e. Marco Polo] because they are both Christian is utter nonsense. It is indeed correct that three hundred years previously, certain Ethiopian kings ruled far and wide in Asia, especially in Drangiana, at the ends of Susa, and in India, until the emperors of the Tartars expelled them from all of Asia, and they were the first ones defeated, so they say, by Chingis, King of the Tartars, having killed their emperor Uncam... all those Ethiopians who had been thrown out of the kingdom of the Mongols and Chinese and were driven all the way to furthest Africa.