The Ming Dynasty (1369–1644) oversaw some dramatic developments in China. There was an increase in the production of manufactured goods, and many cities were founded. The Great Wall of China was renovated and completed. Ming rulers also oversaw the culmination of Chinese contact with the outside world. China was a major maritime power and engaged in Indian Ocean trade, possibly venturing as far as the Atlantic Ocean between 1409 and 1433. The naval fleet of Zheng He, which consisted of three hundred ships, serves as evidence of the advanced shipbuilding and navigational expertise of the Chinese at the time. Construction of the fleet required dry docks and specialists in a number of trades. The ships had as many as nine masts, twelve sails, and multiple levels, and they were over one hundred meters long, dwarfing anything the Europeans had at the time. At least some were mounted with bronze cannons. Historians debate the primary purpose of the fleet. Some believe it was intended to project power abroad.
The fleet was mysteriously destroyed after Zheng He's death. At that point, the Ming turned inward. Some historians point to the large expense of keeping up the fleet. Others hypothesize that the merchants became too powerful for the emperor's liking. Yet others believe that the trade contributed to materialism, which was deemed a threat to Chinese culture. The fleet fell victim to neglect and destruction around the time that Europeans began to enter the Indian Ocean, in the 1490s and early 1500s, but there does not appear to be a direct causal connection between the two developments.
European Christian missionaries seem to have made an appearance in China as early as the eighth century, but thereafter, contact was sporadic and episodic until the early 1500s. In the 1510s, Portuguese traders arrived in coastal China. At this point, we can speak of concrete reactions. Coastal traders showed interested in some of the goods the Portuguese had to offer, with pepper being prime among them. Meanwhile, the Chinese government sought to keep tight control over their territory and immediate periphery, which included limiting trade to port cities, like Guangzhou (Canton). The Chinese rulers, having been supreme in their part of the world, were not particularly interested in foreign goods. There were not many European things that the Chinese state considered particularly impressive. So there was a tension between the position of the state and that of the traders on the coast. Outsiders were largely regarded as a nuisance. By the early 1520s, the state got fed up with Portuguese, owing in large part to their seizure of Malacca and their bad behavior on the Chinese coast, which included illegal trade and even the kidnapping of girls. The Portuguese continued to push trade contrary to the desire of the state, and this led to open conflicts, culminating in the imprisonment and sometimes execution of Portuguese traders.
For further reading, see Chapter 3 of Boundaries and Beyond: China's Maritime Southeast in Late Imperial Times by Ng Chin-keong.