The Inner Circle
The Inner Circle is the underground of Sevess. Beneath the surface is a network of caves and caverns speckled with ancient arcane buildings and machinery, guarded by the denizens of the underground.
These denizens include ancestries like goblins, drow(?), duergar(?), anadi, and others typically viewed by surface society as... Undesirable.
The feeling goes both ways.
Running through these cultures is a belief that they are the custodians of Sevess, an almost religious reverence for the arcane inner workings is baked into their society and informs much of how they act and function.
Though the structures they service largely are made for the regulation of surface biomes and climates, they serve secondary functions for the underground denizens. Food, water, medical care, and more are often built into the enchantments, reinforcing the religious importance in these societies. The relationship is symbiotic, both biological and arcane components of The Inner Circle supporting and caring for one another.
In practice, these societies should feel somewhere between the very cliche "natives who are in touch with the land" trope, mixed with religious zealotry and arcane engineers. They are wickedly book smart and technical as cultures, while feeling a genuine connection to their surroundings. Even if those connections were artificially made and reinforced by Sevesahr.