March of the Machines

From the introduction: Long, long ago an artificer built a mountaintop factory and mining complex operated by clockwork automatons. When the artificer died the workshop was forgotten. Centuries later, a clan of gnomes settled the area and prospered. Meanwhile, aarakocra had roosted in the workshop and kobolds occupied the mines. Then jealous humans drove the gnomes underground, who in turn pushed the kobolds to the deepest recesses of the mines below.