The Jiajing wokou raids caused extensive damage to the coast of China in the 16th century, during the reign of the Jiajing Emperor (r. 1521–67) in the Ming dynasty. The term "wokou" originally referred to Japanese pirates who crossed the sea and raided Korea and China; however, by the mid-Ming, the wokou consisted of multinational crewmen that included the Japanese and the Portuguese, but a great majority of them were Chinese instead. Mid-Ming wokou activity began to pose a serious problem in the 1540s, reached its peak in 1555, and subsided by 1567, with the extent of the destruction spreading across the coastal regions of Jiangnan, Zhejiang, Fujian, and Guangdong. Historical background Maritime trade in 16th century China Up until the establishment of the Ming dynasty in 1368, China had had a great maritime trading tradition that extended the Chinese trading network by sea all the way into the Indian Ocean. In 1371, the Ming founder Hongwu Emperor implemented the "maritime prohibitions" (haijin), banning all private sea trade in order to clear the seas of all piratical elements. Under the prohibition, all maritime trade were to be conducted through the officially sanctioned "tribute trade", which was a kind of trade where foreign states presented tributes to the Chinese court, acknowledged themselves as vassals of the Ming, and received gifts as a sign of imperial favour. This trade, in addition to being humiliating to the foreigners involved, was inadequate to the demands of the markets, both domestic and foreign, since the Ming had strict rules about how often a vassal could come to present tribute. Still, the tribute trade, being the only legal form of trade with China, was extremely profitable. Hence many states, including Japan, were willing to subject themselves to the rituals of the Chinese tributary system. The Japanese were assigned the Zhejiang city of Ningbo as their port of entry into China, and were allowed to present tribute once every 10 years. These Japanese missions to Ming China continued up to Japan's Sengoku period, when the hold of the Ashikaga shogunate waned and power became divided by the warring regional daimyōs. These internecine feuds reached China in the Ningbo Incident of 1523, when traders from the Ōuchi clan fought with those of the Hosokawa clan in Ningbo for the right to present tribute, which spiralled out of hand and resulted in the widespread pillage of Ningbo. When a