The history of the samurai sword is closely related to the history of Japan. Sometime before 650 AD, China and Korea introduced weapons making to the Land of the Rising Sun, and many artisans and smiths from the two countries moved to Japan. At this point, blades were straight and there was still plenty of room for improvement in the art of sword making. The Nara period (650-793) was the golden age of architecture, sculpture, painting, and religious art. Though handmade samurai sword making was still primitive, it had moved forward. This era also saw many wars; thus, the demand for swords increased.
During the Heian period (794-1191), Japan began to “Japanize” imported practices and ideas. Smiths started to incorporate their own distinguishing styles into the samurai swords they made. By this time, Japanese sword making had greatly improved. The samurai became a prominent social class in the Kamakura period (1192-1336), and many of them began to follow Zen Buddhism. The Mongol invasions of Japan (1274 and 1281) prompted further development of the Japanese sword and samurai armor. When the samurai learned that their swords were no match for the thick leather armor of the Mongols in hand-to-hand combat, Japanese swordsmiths started to experiment with different types of steel and metal in order to improve the sword. Some smiths implemented slimmer and simpler temper lines, while others made blades with larger points and wider backs. The Kamakura period came to be known as the Golden Age of Swordmaking – when the most prized japanese katana swords were made.
The demand for swords and other samurai weapons continued to grow during the Muromachi period (1337-1573), also known as The Era of Civil Wars. The immense need for swords, combined with the viciousness of battles, caused practical and disposable weapons to be preferred over artistic ones. It was also during this era that the uchigatana was created, in response to the samurai’s need for a sword for use in close quarters. The uchigatana later became the modern katana and replaced the tachi as the primary samurai sword. The Azuchi-Momoyama period (1574-1602) was more peaceful, and the arts, including the art of sword making, flourished. Smiths began to make high quality swords once more.
According to legend, the swordsmith Amakuni made the first samurai sword (tachi) in Yamato around 700 AD. He was the head of a group of swordsmiths tasked to make weapons for the Emperor of Japan and his warriors. One day, Amakuni and his son, Amakura, were watching the Emperor’s army return from war. The Emperor ignored Amakuni, which was unusual as he had always acknowledged the smith. Amakuni then saw that almost half of the warriors were carrying broken swords. He vowed to make a sword that will not break, and he and his son went to work for thirty one days, after which they emerged from their workshop with a single-edged sword with curvature.
For the next months, Amakuni and Amakura persisted, forging several types of enhanced samurai swords. There was another war in the following spring, and when the Emperor and his warriors came back, all swords were intact. This time, the Emperor praised Amakuni, calling him “an expert swordmaker”.