Katana

A katana is a Japanese sword with a curved, single edged blade over 60 centimeters long, a circular or squared guard and a long grip built for two hands, its name derived from a Japanese term for a one sided blade. It emerged during the Nanboku-cho period, 1336 to 1392, evolving from a shorter secondary blade called the sasuga that lower ranking foot soldiers had carried since the Kamakura period as tactics shifted toward longer weapons. Smiths forge the blade from tamahagane, a layered steel of varying carbon content produced by traditional smelting and repeated folding to remove impurities, and create its curve through differential hardening, coating the blade with clay of varying thickness before quenching it in water so the edge cools and hardens faster than the spine. Beyond its use as a weapon, the katana became a symbol of samurai authority, especially during the relatively peaceful Edo period, and is regarded by Western historians as among the finest cutting weapons in world military history.