As a way to preserve raw fish, the very first sushi was created in Southeast Asia. The narezushi was the first version of sushi. It involved salting raw fish, then putting it in fermented rice barrels. This allowed the fish to go through fermentation. The rice was thrown away and the only thing that was eaten was the fermented fish. Despite it being described as unpleasant, this method allowed fish to be kept for up to a year without spoiling. According to food historians, this type of sushi was created in Southeast Asia around the 5th-3rd centuries BCE. This predates refrigeration by more than a millennium.
Acording to Sushiincorporated.com
