Although materials were scarce to learn the detailed process used at that time, it is believed that sushi originated from 'honnare' sushi (genuine fermented sushi) referring to Nare-zushi which was made by fermenting fish (or meat) with salt and rice, and was eaten after removing rice (Kumano region has yogurt-like 鮓 (sushi) called 'Honnare-zushi,').
当時の詳しい製法を知る資料には乏しいが、魚（または肉）を塩と飯で漬け込み熟成させ、食べるときには飯を除いて食べるなれ寿司「ホンナレ」の寿司と考えられている（ただ、熊野地方には「本馴れ鮓」と称するヨーグルト状の鮓がある）。