Beginning from the early 17th century, the Tokugawa shogunate followed a policy of seclusion, known as sakoku in Japanese language. They suspected that traders, merchants, and missionaries from Europe wanted to bring Japan under the control of European powers. All traders and missionaries from other countries were forced to leave Japan, except for the Dutch, the Koreans, and the Chinese. Even during the period of seclusion, the Japanese continued to gain information and knowledge about other parts of the world.