Mongols. Genghis Khan and his successors united all of Central Asia under one empire. The Mongol rulers took a liberal attitude toward religion, national allegiance, and social customs, and travel within and outside the empire became possible. The establishment of the great Yuan dynasty (1279-1368) and the increase in trade along the Silk Road facilitated the creation of the first direct contacts between China and the West. For the early travelers the most ordinary motivation was commerce, but some had political purposes in seeking allies against the Muslims. Meanwhile, for some travelers, proselytism was the major reason for their trips.

New Route. By 1279 the lands of East Asia had been in touch with the Indo-Iranian world via sea lanes and a land route following a group of oases in the Tarim basin. The Mongol expansion in the thirteenth and...