550 THE HISTORY OF MEDIEVAL EUROPE them as allies against the Moslems in the East and even of Relations of converting them to Christianity. Ambassadors Christendom were dispatched from the West to the court of with the tfie khan anc | Roman Catholic missionaries also Mongol Empire went out to the Far East, where hitherto only Nestorian Christians had been known. Of the letters, re- ports, and books written by such travelers to Asia and by merchants like Marco Polo, we have already spoken in dis- cussing the knowledge of geography in the Middle Ages. Kublai Khan, at whose court and in whose employ Marco Polo spent so many years, had taken up his residence in Peking and had adopted much of Chinese civilization, al- though in the summer he still migrated, in nomad fashion, north to his native Mongolia. The envoys from the West failed to effect much of diplomatic advantage in their long- distance interviews with the khan, and the missionaries had no lasting success. The western Tartars were gradually con- verted to Islam, and those in China adopted the heathen faiths current there. In 1 368-1 370, however, the Chinese revolted and drove the Mongols out of their land. The fact that the whole breadth of Asia was under the despotic rule of a single head made it easy to trade with the Trade routes ^ ar East. The Great Khan was feared far and to the wide, for he maintained relays of swift horse- men between the different parts of his extensive empire, to keep him informed of what was going on ; and his dreaded cavalry would have descended rapidly upon any region that disregarded his commands or attacked persons who were under his protection. The shortest trade route to Cathay and Peking from Europe was the northern one from ports at the mouth of the Don or on the Sea of Azov. This ran north of the Black Sea, beyond the Volga, past the Caspian Sea and then across the expanse of central Asia. From Trebizond on the south shore of the Black Sea, and also from the Cilician ports of Lesser Armenia, trade routes converged on Erzerum, and thence led to Tabriz, which was the chief market of western Asia under Mongol rule. A Spanish traveler in 1404 described it as containing over two
