The Black Ships (黒船 kurofune) was the name used by the Japanese to describe the Western sailing ships, which arrived at Japan's shores between the 15th and 19th centuries.
The most common association, however, is with the four steam-assisted boats of Commodore Matthew Perry, namely "Mississippi", "Plymouth", "Saratoga" and "Susquehanna". Their arrival in Uraga Harbour, Yokohama, on 14 July, 1853, signified the beginning of the end of Japan's self-imposed years of isolation.
The word "black" refers to the black colour of the sailing ships, as well as the black smoke that issued from the coal-powered steam engines of the American ships. However, following the turmoil that followed their arrival, the term "black ship" was used by the Japanese to express a fear, or mistrust, of unknown technology. 
- Satō, Saburō, The Structure of a Tragedy through the Coming of the Black Ships, 2000, pp. 182-195