In 1603, Tokugawa Ieyasu, emerged victorious as shogun. He started a dynasty that will hold power until 1868. He established his capital at Edo which he later called Tokyo. After the war, Ieyasu realized that Europe was growing ties with Japan. Merchants and missionaries had brought western ideas and goods to Japan. He was concerned about the changes that the foreign ideas would bring to the country, so he drove out  merchants and missionaries, banned Christianity, and killed all the Japanese Christians. They also forbade anyone to leave Japan. In the mid 1600's, Japan went into a period of isolation that lasted until the 1850s.