Ultoksamrin was situated beneath the eastern Marching Mountains in Calimshan and the Forest of Mir. The former subkingdom consisted of the ruling cavern, a 1000-ft-high (300 m) grotto, a mile beneath Mount Sarengard, and of several tunnels.
After the fall of Old Shanatar, the former subkingdom Ultoksamrin was emptied of dwarves. By 1372 DR, several non-dwarf races occupied territory of Ultoksamrin's tunnels. The different races fought over additional territory.
The ones who were most successful at it were the drow. These drow were followers of the deity Vhaeraun and were escapees from Guallidurth, from where they fled religious persecution. They were situated in the Vault of Cloaked Midnight, the cathedral city. The temple of the city covered about half of the ruling cavern and the drow lived in former clanholds of the dwarves for protection.