There are many similar seafood-based sauces in regional cuisines, both modern and ancient. Garum originated in Greece, and was extremely popular in ancient Rome.
Etymology: Greek, from garon, a fish often used to make the sauce.
From The Permaculture Book of Ferment and Human Nutrition:
"It was made from cleaned fish intestines, livers, blood, small fish, and trimmings of fish pickled in layers of sea salt, and cured for weeks in the hot sun....The enzymes from the livers and intestines are needed to hydrolize the protein in fish scraps and offal, so that the sauce contains as much protein as the waste."
Apicius, a collection of Roman cookery recipes, contains numerous references to garum.