For generations, before the Urbish Mining Co. had been set up, the Urbish Caves had been a trap for dungeon-pillaging heroes. While wonderful treasure could be found in it's depths, so too danger. Of the few people who made it back to the surface, most came back insane, horribly diseased or even undead.
Four or five generations ago, Vaelan of the Sindari descended into the caves and returned seven years later, all the richer. He claimed to have a way to tame the demons inside, but kept the knowledge a secret. Ultimately, he was found murdered not a year later by someone hoping to discover it.
The deed to the mines passed on to the Laird of House Urbish, who by some means came in possession of the very same "key". While he failed to uncover the fabled treasure as Vaelan did, he did set up a mining company to extract its rich ore deposits. The influx of workers from throughout the Lands to work the mines explains how Gladstone and the surrounding lands came to have such a diverse population.
However, the riches from the mine also brought forth a terrible curse. People said that the Laird's heart wasn't as pure as Vaelan and so couldn't withstand the evils of Urbish. Whatever the case, House Urbish suffered disaster after disaster till the house fell not even three generations after mining began.
It is said that at the very heart of Urbish lies an ancient priests' temple and this is where the Nether Mask could be found. It is also said that this temple was but one part of a great fallen city of the Ancients. Since Scotia's excavation strange activity has been reported around the caves and surrounding areas. Supposedly whatever magical barrier kept the monsters and haunted confined within was shattered when she broke it to take the Nether Mask.