“And they called it a mine… a MIIIINE!!!”
This out of the way system of caves probably wasn’t a very lucrative endeavor for those who extracted precious metals or gems or black lung here, but it’s definitely an interesting place to locate a threat of kobolds, possessed or unionizing miners, or assorted ruffians. As well, maybe it’s not entirely played out. Maybe there’s still wealth to exploited here if you can press these kobolds into service or break the will of the poor souls just looking for weekends off and safe working conditions. A perfect job for PCs.