Let’s look at the diagram below. It may be easier to understand what I am describing by referring with this diagram.
This is the time line divided according to the historical period. The top short line is the time of Joko-to period (上古刀). When we mention Japanese swords, we indicate swords made after Heian Period(平安). Swords made before Heian period are called Joko-to(上古刀). Usually, Joko-to is in the category of the archaeological study. In the next section, Joko-to and pre-Heian period will be described. The bottom time line is the way we see on history books and school history books. The middle time line and the bottom line are almost same, but the middle time line is more useful for the sword study. My blog will follow the middle line. Please keep checking back with this diagram occasionally. We group together the swords by trends of the time of shape and style.
Tachi(太刀), Katana(刀), Wakizashi(脇差), Tanto(短刀).
Swords made before Muromachi period (before 1392) are called Tachi (f太刀). Swords made after the Muromachi (室町) are called Katana(刀) and wakizashi (脇差). Tanto is a short dagger. Tanto was made through out the time. Difference between Tachi and Katana is how they were worn. Tachi was suspended from the waste belt, the blade side facing down. Swords maker’s name was inscribed facing outside on its hilt when it was worn. Katana and Wakizashi (called Daisho -大小- means large and small) were worn inside the belts, the blade side up. Swords maker’s name was inscribed facing outside on its handle when it was worn. When you face the maker’s inscription, if the blade comes on the right, that is Tachi. When you face the maker’s inscription, if the blade comes on left, that is Katana and Wakizashi.
Ko-to(古刀)、Shin-to(新刀) Shinshin-to(新々刀) Gendai－to (現代刀)
Ko-to is the swords made from Heian period(794-1192) to the beginning of Keicho Era(1596-1615). Shin-to is the swords made from around Keicho Era (1596-1615) to Tenmei Era(1781- 1789). Shinshin-to is the swords made during Bakumatu time (幕末期1781-1868). Gendai-to is the sword made after Maiji revolution(明治1868) until now.