There might even be a directish connection, one way or the other, between garum and SE Asian fish sauce, since Roman coins have been found in Vietnam.

Can't find the better source on that specifically now but this is a nice article about the Roman trade with India and mentions the coins found in Vietnam and even Korea about half way down

https://www.thecollector.com/why-was-the-roman-indian-ocean-...

On the other hand, it's not implausible that maritime societies come up with their own fish sauce independently