During the Meiji period, mine development was promoted under the policy of the Fengoku Robe , and coal mining, Ashio Copper Mine, and Kamaishi Mine with iron ore in Hokkaido and northern Kyushu were developed. The production of high-value gold and silver, even in small quantities, was at the top of the world. An important mine was the Ashio Copper Mine which existed since at least the 1600s. It was owned by the Tokugawa shogunate. At that time it produced about 1,500 tons annually. The mine was closed in 1800. In 1871 it became privately owned and reopened when Japan industrialized following the Meiji Restoration. By 1885 it produced 4,090 tons of copper (39% of Japan's copper production).