Owing to the ancient Northwest Silk Road cut off by the Xixia troops and the economic center shifting from the North China to the South China, the coast of southeast China had become the new trading center for its busy ports since the Song dynasty (960-1279).
Only one Shi-Bo-Si (a department in charge of foreign trade) was established in Guangzhou during the Tang dynasty (618-907), and a number of Shi-Bo-Si were successively built in Guangzhou, Lin’an (present Hangzhou in Zhejiang Province), Qingyuan Prefecture (present Ningbo in Zhejiang Province), Quanzhou (in Guangdong Province), Jiaxing Prefecture (present Songjiang), Zhenjiang Prefecture (in Jiangsu Province), Pingjiang Prefecture (present Suzhou), Wenzhou (in Zhejiang Province) and Shanghai Town (present Shanghai) in the Song dynasty, when Quanzhou boasted the biggest port in the world and the starting point of the ancient Maritime Silk Road. The overseas trading was composed of the state-run ones and the private-run ones in the Song dynasty, of which the latter was in the majority China’s silk road economic belt.
The Regulations on Administration of Guangzhou Port drew up by the Song government took effects in the third year of Yuanfeng Period, which was the first law of trade in Chinese history. The alien markets were successively established near the trading ports across the nation, exclusively selling the foreign merchandises, and the alien blocks were also built in the major overseas-trading cities for foreigners, so it was with the alien schools. The punishment acts for the alien merchants were specifically stipulated in the law of trade, and the visitors can see lots of tombs for the ancient alien merchants in Guangzhou and Quanzhou now, which witnessed the prosperity in overseas trading in the Song dynasty.
More than 58 countries had trading relations with the Song Empire during the Song dynasty, including Persia (present Iran), Dashi (present Arabic countries) and Daqin (present Rome), when the ancient Song people mainly exported silk fabrics, porcelains, sugars, tea, textile products and ironware to the foreign countries and imported ivories, corals, carnelians, pearls, mastics, myrrh, peppers, colored glazes and hawksbills from the foreign countries.
The Song Empire gained substantial profits from the overseas trading, which ranged from 530,000 taels of silver in Huangyou Period (1049- 1054) of the Northern Song dynasty (960-1127) to 2,000,000 taels of silver in Shaoxing period (1131-1162) of the Southern Song dynasty (1127-1279) according to the historical documents, taking up 6% of the total government revenue, so the overseas trading played an important part in promoting economic prosperity then.