A tachi (大刀) is a type of traditionally made Japanese sword (nihonto) worn by the samurai class of feudal Japan. Tachi and katana generally differ in length, degree of curvature, and how they were worn when sheathed, the latter depending on the location of the mei, or signature, on the tang. The tachi style of swords preceded the development of the katana, which was not mentioned by name until near the end of the twelfth century. Tachi were the mainstream Japanese swords of the Kotō period between 900 and 1596. Even after the Muromachi period (1336–1573), when katana became the mainstream, tachi were often worn by high-ranking samurai.