Do you have a save or worldgen parameters you can upload? I've always wanted to play a world with no migrants and traders.
Sadly the save is part of my Svartalfheim quasi-alpha, which I'm not willing to upload as of yet, especially as it still has tons of masterwork civs-features I plan on cutting.
Did some further research into this world today. Apparently the dwarves had it bad from the get-go. In the year 1 they founded the only two fortresses they ever would. Fortifygrowl and Knightlygeared. The dwarves had chosen to dwell in a mountain range bordered only by glaciers and deserts in the far north. Every year they would be invaded by beasts most foul. Orcs. Muspel. Hrimthur. Warwolves. Every year the enemy would be driven back. While the elves and humans flourished in the extreme south (the elves have well over a dozen forest retreats), the dwarves had no other friendly civilizations to draw the attentions of their enemies in the bitter north. Even so, their first settlement didn't fall until the year 67. Knightlygeared, ever the less prosperous of the two cities, finally fell to the Hrimthur. Fortifygrowl, having fended off opportunistic human incursions for the past 3 years, would collapse in the face of a Muspel onslaught two years later, being led by the last general of their civilization, Vucar Midnighthorrible.
Truly, this is the most grimdark world I've ever genned up. Although the humans attacking the dwarves in the last few years of their existence sorta confuses me.