Fish sauce called Garum was a valuable ancient Roman sauce/flavouring and was traded and coveted by Roman soldiers. An ancient roman shipwreck off the coast of spain has revealed hundreds of amphorae that still contain Garum. Apparently Romans loved Spanish garum the best and there was a lot of trade between Spain and Italy.

Here is an ancient recipe for garum:

Ancient Garum Recipe Use fatty fish, for example, sardines, and a well-sealed (pitched) container with a 26-35 quart capacity. Add dried, aromatic herbs possessing a strong flavor, such as dill, coriander, fennel, celery, mint, oregano, and others, making a layer on the bottom of the container; then put down a layer of fish (if small, leave them whole, if large, use pieces) and over this, add a layer of salt two fingers high. Repeat these layers until the container is filled. Let it rest for seven days in the sun. Then mix the sauce daily for 20 days. After that, it becomes a liquid.
Gargilius Martialis, De medicina et de virtute herbarum, reprinted from A Taste of Ancient Rome

Read more about this discovery atGiant Roman Shipwreck Yields “Fishy” Treasure