The PCs in the game I'm running aren't dwarves. They are members of the aforementioned refugee class - most of whom are humans.
Seventeen years ago, the sky went dark. The surface became uninhabitable and nearly devoid of life. Horrors came out from the dark corners of the world to which they had been banished.
Some few surface dwellers took shelter where they could. Kor was one of the places they were welcomed. Still, the dwarven society changes slowly... and it was not built to accomodate a sizeable minority of non-dwarves.
The game is going to focus on political intrigue, mystery, prejudice, and destiny... with a healthy dose of high weirdness.