In the Onyx Enmity War (915 - 920), Runelderil lost 90% of its population when the Nermanis Sea flooded their territory. Most of survivors went northeast where they founded their new capital Ghaundan. Others with no interest in starting over, went to established settlements like Mulun-Dûna and Fermin.
Runelderil is atypical of drow societies. It is an empire with a long line of rule by males. Perhaps even stranger, worship of Lolth is unheard of in the empire. Worship of the Demon Queen disappeared more than a thousand years ago. In the Second Epoch, proselytizers of the Khazarkar Empire began spreading the word of Set into Ghaundan. When several drow houses tried to stop the proselytizers of Set, they were wiped out by forces backed by the Khazarkar Empire. These houses, and rightly so, believed that the Khazarkar Empire were using religion to infiltrate their society and turn them into a puppet state. Geb is another of the city's deities. Worship of him spread to Runelderil by way of a powerful Church of Geb based out of Mulun-Dûna.