プラノ・カルピニ
The warlike tendencies of the Mongols also concerned the Pope, and in 1245, he issued bulls and sent a papal nuncio in the person of Giovanni da Pian del Carpine (accompanied by Benedict the Pole) to the "Emperor of the Tartars". The message asked the Mongol ruler to become a Christian and stop his aggression against Europe. The Khan Güyük replied in 1246 in a letter written in Persian that is still preserved in the Vatican Library, demanding the submission of the Pope and the other rulers of Europe.