Tang and Overseas Trade. By the Tang era (618-907) there was extensive sea trade with Japan and Korea. The Japanese and Koreans entered China by way of the mouth of either the Huai or Yangzi (Yangtze) rivers at Hangzhou, thence by canal to the capital, Chang'an. They did not use the Yellow River because it was not navigable in its upper reaches. The ordinary crossing from Japan to China took from five to ten days. Many Buddhist monks and pilgrims also traveled on this route, carrying incense and medicines from China to Japan. In addition to Japan, the Tang court had significant connections with Arab and Persian lands. Hangzhou was the principal port, where thousands of Arab and Persian traders lived.

Song Maritime Techniques. Many improvements in seafaring occurred in the Song period. Through experimentation the Song people...