From RocksfallWiki

Colony of Stordam. Vinmark was mostly started to interfere with lumber production in Mariannas: Mariannas provided a lot of lumber for the Gallic fleet, which was a threat to Stordam, which had holdings on Gaulle's home island. Stordam ended up deploying some troops to Callidora to disrupt that trade, and they allied with the Atenrosera who had been resisting Mariannan expansion.

The Atenrosera are benefiting from the fact that Stordam doesn't really want Vinmark as much as they just don't want Gaulle to have it. So they haven't been really pushing too much. They trade furs and stuff with the Atenrosera, but mostly it's a live and let live situation. Stordam got a lot of really good land, they just haven't settled it too densely yet.