Fun facts, the closest to ancient Roman fish sauce (garum) in ingredients today is probably Vietnamese fish sauce[1][2]. This is probably not only the source for the umami flavor but also the natural salty ingredient without the modern salt. This is not surprising since majority of Vietnam today (Central and South Vietnam) was ruled by Champa kingdoms until 16th century but Chams people were then evicted by the Nguyen lords from the North. Chams, Malay and Indonesian languages (top ten most popular languages in the world) has the word "garam", for salt and it is probably originated from the word garum.
If you want how ancient Pompeii lived and ate, please check this excellent video by Absolute History[3].
If you want how ancient Pompeii lived and ate, please check this excellent video by Absolute History[3].
[1]https://scmp.com/lifestyle/food-drink/article/3094604/did-fi...
[2]https://en.m.wikipedia.org/wiki/Garum
[3]https://www.youtube.com/watch?v=LSw7eoBbM0U