Kang Xi (1662-1722) was the second emperor of the Qing Dynasty, and Qian Long (1736-1795) was the fourth. In the early years of the dynasty, when Zheng Chenggong and others were leading anti-Qing armed struggles in the coastal areas of southeast China, the government placed a strict ban on maritime intercourse with foreign countries, forbidding the people to go to sea and imposing severe restrictions on foreign trade. It was only after the government reunified Taiwan with the mainland in 1683 that merchants were allowed to build ships and go to sea. In 1685 the Qing government designated Macao (later replaced by Guangzhou), Zhangzhou and Ningbo as ports open to foreign merchants. Later, when Western colonialists began to engage in illegal activities in China, the government, which was becoming increasingly conservative, took only weak measures to prevent them. In 1757 it closed down all the coastal ports except Guangzhou and laid down many regulations to restrict foreign merchants' trade in China. This situation remained unchanged until the outbreak of the Opium War in 1840 (see note 34).