Archaeological evidence indicates that swords have existed in Japan for its entire historical period. Short straight swords imported from China and Korea are among the earliest weapons found in historical sites around Japan. After 2000 B.C., when these swords first appeared, the Japanese began making their own swords. Around 700 A.D., Japanese swordsmiths forged the first of what are now considered the finest swords ever made. The person considered responsible for vastly improving Japanese sword design and manufacture was a smith named Amakuni. Like others in his profession, he was responding to the huge demand for weapons made by local, provincial, and national leaders. Regional conflicts over land rights and issues of power continuously erupted, and, when not warring among themselves, the early Japanese were invading the Korean peninsula or China, or defending themselves against Korean and Chinese invaders. Any leader with a supply of superior weapons was at a great advantage, so a constant, long-term effort to find swordmakers improving the craft ensued. The most devoted smiths made the quest for the perfect blade into a lifetime pursuit, and men exist today who devote their lives to the art of swordmaking. The long sword in Japan has seen three major incarnations, and for each type of sword exists a fighting style to match the blade's shape. The early blades, called chokuto or “straight swords,” tended to get longer as metallurgy techniques improved. Though not much is known about how these weapons were wielded, the extra length - without any significant increase in weight - certainly gave the fighter more reach. The handle size of these blades suggests that they were held in one hand. The two-edged blade suggests a thrusting and hacking style of fighting. The first major change in the shape of the sword came during Amakuni’s time, a style perhaps created by Amakuni himself. Warriors found that, compared to a straight blade, a curved sword can be drawn from the scabbard more quickly and can provide a more effective cutting angle.
Consequently, swordsmiths developed forging techniques to make a curved blade at least as strong as the earlier straight ones. These swords, called tachi, were extremely long, some nearly four feet, and were generally used by soldiers on horseback. The long, curved blade was ideal for a sweeping draw and slash against opponents on the ground or mounted upon other horses. Later in Japanese history, most soldiers found themselves doing battle on foot, or engaging in individual combat against one another. For such men, the tachi were too long to be drawn or wielded comfortably, so a shorter sword was developed. This sword was the katana, and the katana is the sword that most practicianers of Iaï-Do systems use today. Katana are generally between two and four feet in length and, though curved, have a less pronounced arc than the tachi. They can be efficiently drawn from the scabbard into position for a horizontal, diagonal, or vertical cut, and the curve of the blade lends itself well to the efficient slashing cut characteristic of Iaï-Do.
Katana (刀:かたな) is a type of Japanese backsword or longsword (大刀:だいとう daitō); the term is also frequently mis-used as a general name for Japanese swords. In use after the 1400s, the Katana is a curved, single-edged sword traditionally used by the samurai. Pronounced [kah-tah-nah] in thekun'yomi (Japanese reading) of the kanji 刀, the word has been adopted as aloan word by the English language; as Japanese does not have separate plural and singular forms, both "katanas" and "katana" are considered acceptable plural forms in English. The katana was typically paired with the wakizashi or shōtō, a similarly made but shorter sword, both worn by the members of the warrior class. It could also be worn with the tantō, an even smaller similarly shaped blade. The two weapons together were called the daishō, and represented the social power and personal honor of the samurai. The long blade was used for open combat, while the shorter blade was considered a side arm, more suited for stabbing, close quarters combat, decapitating beaten opponents when taking heads on the battlefield, and seppuku, a form of ritual suicide. Japanese swords are fairly common today, antique and even modern forged swords can still be found and purchased. Modern nihontō are only made by a couple hundred smiths in Japan today at contests hsted by the All Japan Swordsmiths Association.