This pungent southeast Asian fish sauce is usually made from anchovies, salt and water. The fish is fermented in wooden boxes or barrels, then pressed to produce intensely flavoured salty and fishy liquid "salt".There are many similar versions and variations which are used throughout Southeast Asia: Indonesian trasi, Cambodian prahok, Malasian Krill, belacan and budu, and the Filipino Indochinese patis. Nam Pla is used instead of table salt to complete the Thai combinations of salty, sweet, hot and sour and as well as used as a cooking ingredient, can also be used as a dipping sauce or condiment with the addition of chillies, which is called Nam Pla Prik in Thai.
Interestingly, the Classical Romans had their own version, called garum or liquamen, and there are other deviations mixing with either vinegar or honey. The Romans used a variety of fish including tuna, mackerel, moray eel, and anchovies. A much later development transformed into Worcestershire sauce.
