In the 12th and 13th centuries, while the Mongols were swiftly expanding their dominion across Asia, Dominican and Franciscan friars began to establish convents from Eastern Europe all the way to Armenia, Georgia, and Persia. By the end of the 13th century, when Marco Polo (1254-ca. 1324) was heading home after two decades spent in the lands of Kublai Khan (1215-1294), the Franciscans reached northern and eastern Tartary; in the early 14th century, they founded a vicariate in Cathay. Their missionary activity was decisive in the acquisition of geographic knowledge of the Far East. Together with Marco Polo’s Marvels of the World (Il Milione), the travel accounts by Franciscan and Dominican missionaries laid the foundations of the geographic knowledge that allowed Medieval Christianity to expand the image of the world inherited from classical antiquity. While observing early modern maps of the world we can understand how a 15th-century humanist cartographer would regard the travels of mendicant-order missionaries as the events that ushered in the modern world—in other words, that revealed the part of the world unknown to the ancients or at least not described by them.