Sir John Mandeville notes in his travelogue -- read and carried by Christopher Columbus -- that Trebizond was the “haven of Persians and of Medians” … 

According to the Encyclopaedia of the Hellenic World (2008), Trebizond, located in far northeastern corner of Anatolia and the southern Crimea, was a major commercial center during the 13^th century… bishops from Trebizond were allowed to visit Persia and it’s during this time that the Persian scientific tradition was introduced to Trebizond and Constantinople (Byzantine Empire)… Persian astronomy was taught and Persian manuscripts were translated to Greek in Trebizond… additionally, in Constantinople, “a Byzantine tradition inside the Persian school” was further developed in 14^th and 15^th century which spread to Western Europe…

[pic source pemptousia … for educational purposes only]