Let’s look at the diagram below. At the beginning of each chapter, a timeline like the one below will be shown. It will serve as a useful reference for determining which period is being discussed.

From the Jomon period to the Nara period, (the short top line) is the period we call the Joko-to period in the history of Japanese swords. The term “Japanese sword” as we use it today refers to swords made after the Heian period (平安 794-1185). Usually, Joko-to falls under the category of archaeological study. In the next chapter, we will discuss Joko-to. The bottom timeline, with short descriptions below, is the one we see in Japan’s general history books. The middle timeline is more specific to the study of swords. My discussion will follow the middle timeline. A timeline diagram will appear at the beginning of each chapter for easy reference. The swords discussed in this book are grouped based on their shape, style, and the trends of their era.
The difference between Tachi (太刀), Katana (刀), Wakizashi (脇差), Tanto (短刀)
Swords made before the Muromachi period (before 1392) are called tachi (太刀). Swords made after the Muromachi (室町) period are referred to as katana (刀) and wakizashi (脇差). Katana and wakizashi were worn together. A tanto is a short dagger. Tantos have been made throughout history. The difference between a tachi and a katana is how they are worn. A tachi was suspended from the waist belt, with the blade facing down. The katana and wakizashi (called daisho, 大小, meaning “large and small”) were worn together between the belt and the body, with the blade side up. Usually, a tachi is longer than a katana. A wakizashi is shorter than a katana. The tanto is the shortest. When facing the swordsmith’s inscribed name, if the blade is on the right, that is a tachi. When facing the swordsmith’s inscribed name, if the blade is on the left, that indicates a katana or a wakizashi.
Tachi > Katana > Wakizashi > Tanto

Ko-to (古刀) Shin-to (新刀) Shinshin-to (新々刀) Gendai-to (現代刀)
Ko-to are swords made between the Heian period (794-1192) and the beginning of the Keicho Era (1596-1614). Shin-to are swords made between the Keicho Era (1596-1614) and the Tenmei Era (1781-1789). Shin shin-to are swords created during the Bakumatsu period (幕末期 1781-1868). Gendai-to covers the period from the Meiji Restoration (明治1868) to the present day. Although the names of eras or periods changed overnight due to political or dynastic shifts throughout history, the changes in sword style were always gradual. In general history, the Bakumatsu period is simply the last part of the Edo period. However, for sword classification, it is from around the Tenmei era (天明 1781) to the beginning of the Meiji period (1868).
