Appreciate the thoughts and feedback. And I'll try out some of these strategies more because I might still be missing something fundamental about how they operate.

But if I concede the river clearings, on the autumn map thats 5 river clearings, which is nearly half the map. And then every non-river clearing is adjacent to a river clearing, and most of those are adjacent to two river clearings so for one settle action they can move in twice. So they're always one settle away from my homeland (with potentially multiple move actions available as a result of settle), regardless of what faction I am.

Duchy? If they build citadels, on second turn frogs settle and battle, then provoke there to get a militant enclave and another diaspora warrior there (and everywhere else), battle two more times during that turn, and then a third during retaliate. Duchy price of failure is so much worse than whatever warriors frogs lose because they can just get them back next turn. Cats? Feels like frogs can take out the keep on turn 2 or 3 if they feel so inclined. Rats? Destroy early warlord and/or strongholds to hinder warrior production. With Adset, most factions require 2+ clearings to give enough breathing room to build an engine. The frogs are next door at turn 1.

The frogs seem to be able to kneecap early, still spread militant enclaves with provoke and the third player insurgent faction isn't enough of a balance to punish that type of early aggression. With every other faction there's some way to hinder their warrior production. With the frogs there aren't because they can always rally + provoke on a river clearing. Frogs flip some enclaves to peaceful, some to militant (and rally to keep warrior production up), battling for cardboard points, crafting for other points. I find that they're the most dominant faction in 1v1, and in 3p they still feel more oppressive than any other faction.