Talk:Taroutachi/@comment-180.243.148.121-20150325033321/@comment-1883159-20150326153254

I don't know the exact date, but their swordsmith, Chiyodzuru Kuniyasu, made them after he moved to Echizen during Nanboku-cho period (1336-1392). Sengoku period is about 100 years after that so... yeah, somewhere between then.

An article that features a little bit about the brothers: http://www.fukuishimbun.co.jp/modules/feature/?cat=546&author=55