The tachi was a type of Japanese sword that was primarily used by samurai warriors during specific periods in Japanese history, such as the Heian period (794-1185) and the Kamakura period (1185-1333). The tachi had a longer blade compared to the later katana and was often worn suspended from the samurai's belt with the cutting edge facing down, as opposed to the katana, which was worn with the cutting edge facing up.

The primary purpose of the tachi was for mounted combat, specifically for samurai warriors on horseback. It was a weapon designed for the battlefield and suited for cavalry charges and sweeping strikes. The longer reach of the tachi allowed samurai to engage enemies from horseback more effectively, and the curved blade aided in cutting through opponents or striking with greater force.

The tachi's design and construction were influenced by the needs of mounted warfare, with its longer grip providing stability and control when wielded with both hands. It was a symbol of a samurai's status and served as a primary weapon in battles and skirmishes.

Over time, as battlefield tactics and weaponry evolved, the tachi gradually gave way to the shorter and more versatile katana, which became the favored sword of samurai during the later periods. The katana was better suited for one-handed use and close-quarters combat, making it more adaptable for various fighting scenarios.

While the tachi lost its prominence as a battlefield weapon, it remained a symbol of prestige and was often passed down as an heirloom within samurai families. Today, tachi swords are treasured as historical artifacts and appreciated for their craftsmanship and historical significance.