What is the traditional fermented sushi that predates modern nigiri?

Narezushi is the traditional fermented sushi that predates modern nigiri.

Narezushi is one of the oldest forms of sushi. It was originally a preservation method in which fish was packed with salt and rice and allowed to ferment. The fermentation produced acids that helped inhibit spoilage, while the rice was traditionally discarded rather than eaten.

The method eventually spread from mainland Asia to Japan, where it changed over many centuries. In later forms, including namanare, the fermentation period became shorter and the rice began to be eaten with the fish. Vinegar later replaced much of the slow fermentation process, helping create hayazushi and the quick, fresh styles familiar today.

Narezushi is not simply raw fish served on rice. That description fits modern sushi more closely, especially nigiri. A surviving Japanese example is funazushi from Lake Biwa, traditionally made with fermented crucian carp. It shows how sushi began as preserved fish food long before becoming a fast, restaurant-style dish.