Григорий X
Since Dominican fathers had among their missions that of evangelizing foreign peoples (cf. the role of Dominican missionaries in China and in the Indies), it is reasonable to think that they considered Marco's book as a trustworthy piece of information for missions in the East. The diplomatic communications between Pope Innocent IV and Pope Gregory X with the Mongols were probably another reason for this endorsement. At the time, there was open discussion of a possible Christian-Mongul alliance with an anti-Islamic function. In fact, a Mongol delegate was solemny baptised at the Second Council of Lyon. At the council, Pope Gregory X promulgated a new Crusade to start in 1278 in liaison with the Mongols.