Disrupting Trade

[Old Geezer]

Economic warfare does not seem to be "profitable" to me until at least mid game (100 turns in) because the AI usually is not developed enough for it to hurt and it takes a lot of time to recruit, train, and destroy. It seems to work marvelously well against the Mongols once they have settled. You can drag them down quickly to no longer being the richest faction by destroying their buildings especially stables and archery ranges which they will keep on rebuilding.

[Mek Simmur al Ragaski]

I reckon this would be fairly useful against HRE in the early stages, as if you can stop their income, they have larg armies and they would certainly suffer, also they are spread thin so you could just sack all the cities and kep them so far under they can never recover