 The first of Arghun 's embassies was led by Isa <unk> , a Nestorian scientist who had been head of Kublai Khan 's Office of Western Astronomy . <unk> met with Pope Honorius IV in 1285 , offering to " remove " the Saracens ( Muslims ) and divide " the land of Sham , namely Egypt " with the Franks . The second embassy , and probably the most famous , was that of the elderly cleric Rabban Bar Sauma , who had been visiting the Ilkhanate during a remarkable pilgrimage from China to Jerusalem . 
