Japanese Sword Development

During the Mongolian invasion of Japan (Kamakura period), a great samurai warrior from the Minamoto clan residing in Sagami (the Soshu Province) commissioned a local master swordsmith to create a daito, or long sword. Soon after, he encountered a group of nine armed warriors. With skill and grace, he defeated the group by himself. Before the next battles of the day, he chose to clean his swords. He found a secluded spot, hidden from view in the woods. He pulled from his obi a small black cloth pouch, which held his uchiko (limestone powder), cleaning cloth, and oil of clove. While cleaning and inspecting his newly acquired daito, he noticed the blade was unscathed. His past blades hadn't had nearly the same strength, flexibility or sharpness as this new blade. His strong, sharp sword and expert technique helped him to gain a reputation of fierce excellence. With this sword, the samurai warrior helped his clan along with all of the other samurai clans from Kamakura defeat the Mongols, reinforce the strength of the feudal government and unify the spirit of Japan.
The Japanese samurai sword's development paralleled the history of Japan. Soon after the first empire of Japan was established (roughly at the start of the Christian era), the art of weapon making was brought from China and Korea. The Chinese and Korean swordsmiths taught the Japanese how to make swords, but it was the Japanese who perfected the art of swordmaking throughout centuries. This was largely due to the way the Japanese people were about life-meticulous and idiosyncratic. The swordsmith was clean and reverent, with the greatest respect for every detail. His rituals would include praying, wearing white, and performing misogi purification. The process required complete focus and concentration.
The ancient sword period-also known as the ken or the straight sword period-lasted about 300 years. The swords of this era were made of steel; however, the hardening process was not perfected. The quality of the edge and strength of the sword was affected by the lack of understanding of the hardening process. Some blades were double edged and some were single edged, and they all imitated the Chinese blade styles.
Through the Nara and Heian periods in Japanese culture, swordmaking remained in the ancient period, making little headway. The need for a better quality sword arose.
A legend states that a swordsmith, Amakuni Yasutsuna, was the leader of a group of swordsmiths. They made swords for the emperor and his warriors. One time, Amakuni and his son Amakura watched the emperor and his warriors returning from battle. They noticed most of the swords brought back were broken or badly damaged. They gathered some of the broken swords to examine, realizing that the reason for the failure was due to incorrect forging. So for one week Amakuni and Amakura prayed to the Shinto gods and purified themselves by misogi meditation. Then they gathered the finest ore and refined it to create the first single-edged sword with a curved blade. It was polished and presented to the emperor. The other swordsmiths thought this was insane; however, as the days went on Amakuni and Amakura continued their efforts to improve technique and created many swords in this fashion. The next time the warriors returned from battle, virtually all of the blades they brought back were intact and in excellent condition. (This legend was passed down from the swordsmiths of the Yamato province.)
In the middle of the Heian period of Japanese culture, the next sword period-called koto or old sword period-took place. The need to stay connected to China diminished and the art of Japanese samurai swordmaking leaped ahead. The swords that emerged from the latter part of this era are of the finest made to date and are the most sought after by collectors and the Japanese government of today as examples of national treasures.