During the Goryeo period, Korea had a healthy trade relationship with the Japanese, Chinese, and Manchurians. An example of prosperous, international trade port is South Pyongan Province. Koreans offered brocades, jewelries, ginseng, silk, and porcelain, renowned famous worldwide. But, during the Joseon period, Confucianism was adopted as the national philosophy, and, in process of eliminating certain Buddhist beliefs, Goryeo Cheongja porcelains were replaced by white Baekja, which lost favour of the Chinese. Also, commerce became more restricted during this time in order to promote agriculture. Because silver was used as currency in China, it played an important role in Korea-China trade.
