Instead of the then existing straight swords, curved swords which were more suitable for cutting persons or those suitable for fighting on horseback were developed, and the original model of the current Japanese sword was created.
さらに、従来の真っ直ぐな剣から、湾曲して人を斬りやすく、また馬上での戦いに適した形に進化し、やがて現在まで伝わる日本刀の原型ともいえる剣が登場する。