Japan called the Western ships kurofune (黒船), meaning "black ships," primarily because of their appearance. When Western powers, especially the United States, began arriving in Japan in the 16th and 19th centuries, their ships were often painted black due to the use of pitch or tar to protect the wooden hulls.
The term became particularly famous in 1853 when U.S. Commodore Matthew Perry arrived with his fleet of black-hulled steamships to force Japan to open its ports to foreign trade. The sight of these large, smoke-emitting ships was intimidating to the Japanese, who had been largely isolated from foreign influence for over two centuries under the Tokugawa sakoku (closed-country) policy. The arrival of Perry’s fleet, known as the "Black Ships Incident," symbolized the end of Japan’s isolation and the beginning of significant political and social change.