The Sengoku period (period of warring states) gave rise to mass production of inferior Kazu-uchi mono (mass products), but on the other hand, the steel industry which produced the material made a rapid advance in Tatara (bellows) technology and with the arrival of guns by trading with Westerners.
戦国時代は粗悪な数打物の大量生産を招来したが、一方で原料を生産する鉄鋼業は国内におけるたたら技術の進歩、南蛮貿易による鉄砲の伝来によって急速な進歩を遂げる事になる。