Awa Indigo is a well-known indigo dye produced in the Tokushima region. The indigo is derived from the Polygonaceae plant that is cultivated in the Yoshino river basin. This plant was first cultivated during the Kamakura Era in the Mima-gun region of Tokushima, later shifting to the Oe-gun region. By the Edo Era, the lower river basin of the Yoshino River had become an important centre for indigo production, and with the patronage and protection of the local government, Tokushima became the nation's largest centre for indigo production.
The main ingredient for indigo dying in Tokushima is Awa indigo dye. Its colour emerges during the fermentation process. In this process, finely chopped leaves are fermented to create sukumo, and lye is then added to make the liquid dye. This solution is created in the dyeing house. Cloth is then dipped into this solution and exposed to the air, the colour emerging as a result of oxidisation. This dipping procedure is repeated many times to further deepen the colour.
In 1968, the Awa Indigo dyeing methods were designated as one of Tokushima's intangible cultural assets. This method of dyeing is used in the production of clothes and interior furnishings.