The emperor who abolished the sea ban and established a trading port.

In the fifth year of Yongzheng (1727), Yongzheng was worried that the foreign ban in Fujian and Guangdong would cause a shipwreck, so he agreed to cancel the maritime ban in Nanyang and then open four trading ports in Guangdong, Fujian, Jiangsu and Zhejiang. "But in the 22nd year of Qianlong (1757), western merchants violated the trade regulations of the Qing government, closed the customs of Jiangsu, Zhejiang and Fujian without the order of the Qing emperor, designated foreign merchant ships to trade only in Guangdong Customs-Guangzhou, and imposed strict restrictions on the export of traditional commodities except silk and tea, which set many regulations and restrictions on the overseas trade of China merchant ships. This is what people usually call closed-door. "