A Thaig In The Middle
When the Deep Roads and the dwarven kingdom fell, several of those abandoned by Orzamar were forced to retreat to the surface rather than face annihilation at the hands of the darkspawn. In many cases these were small handfulls of the weak and infirm who had no other recourse but to join with the other surface dwarves and give up all hope of regaining what should have been theirs.
However, that is not always the case.
Three of the larger Thaigs held out for a decade, but then the darkspawn managed to raze their food supplies, and, when faced with starvation they banded together and dug their way to the surface. After being declared surface cast by Orzamar, they cut off ties with the remnants of their former nation and built a city in the mountains surrounding the canyon where they surfaced, always keeping an eye on the deep roads in the hopes of finding a way to retake their former homes.
The recent lul in the darkspawn, allowed them to begin retaking their former homes.
Hearing rumors of the survival of their kin from Kal-Sharok, they have sent emissaries, hoping for a better reception than in Orzamar.
If it were just that, then it would have been of no real consequence, but a couple of the casteless treasure hunters from Orzamar spotted where these emissaries came from and passed word to their patrons of the Thaigs under the control of surfacers.
An expedition from Orzamar was sent by a coalition of several noble houses to "drive off the squatters" and take the Thaig, but was repulsed by this new dwarven nation, but some made it back to their home city.
Orzamar is gathering an army to smash the surfacers who would dare take what belonged to the dwarven empire and slaughter the forces of Orzamar while this surface kingdom prepares to defend their retaken home.
Enter the adventurers...