Military action
As the Silver Kingdom recovered from The Green-Skin Wars, the dwarves of the Ashbight Clan felt resentment not just because of their long-held grudge against the Bronzeheart Clan, but because of what they saw as abandonment by the wider Silver Kingdom in their time of need. Bitterness still clung to their hearts, and hoarded the most valuable gems discovered beneath Druvenholme to themselves to rebuild their hold, yet the rest of the Kingdom demanded they tithe their fair share for the betterment of the whole so that other holds might rebuild.
The Ashbight Clan believed in not only the superiority of the dwarven race to all others but the superiority of their own clan. They looked on with disgust at the Silver Kingdom as it consorted and traded with what they saw as lesser races; humans and halflings, and yet the Silver Kingdom dare ask them to pay their tithe so such treasures might fall into the hands of such unworthy creatures? 'Degeneracy', they said, and refused outright. The Silver Kingdom, they saw, was too busy trading with lesser races to help them in their time of need.
Nearly fifty years went by and bitterness brewed into hatred, which was fanned by the King of Druvenholme at the time, Nogduur Ashbight, a fiery and violent and revolutionary leader. The dwarves of Clan Ashbight banded together underneath him to initiate a siege upon the capital of Duunhollow after they had excavated a Mountainpass highway route that connected Druvenholme directly to the capital city.
Clad in golden armor fashioned and secretly cursed by his personal armorsmith, Bronne Farrikson, Nogduur stormed into Duunhollow's throne room with the full force of his army and personally beheaded King Anbuurn Bronzeheart II. As a warning to the rest of the clan holds, he put the former High King's head on a pike for all to see.
Nogduur's fifty-year reign was one of tyranny, death, and oppression, particularly to non-dwarven races, which only worsened when the armor's maddening curse took hold, and he disgraced his clan's name by slaying and devouring his own daughter, who was next in line for the throne, both as a way to preserve his own seat in power and to appease the voices rumored to torment him at night. This earned him the moniker of 'The Cannibal King' from his dissenters. While known to Bronne, nobody else is quite sure if it was a curse put on the tyrant king by another who thirsted for his throne, or if it was genuine madness that took him in his senior years.
Nogduur's oppressive reign sparked the War for the Silver Crown; a bloody civil war between loyalists of the then Mountain-King Nogduur Ashbight and loyalists to Clan Bronzeheart. The loyalists to Clan Bronzeheart rose up and rebelled, successfully thwarting the Ashbight Clan and killing Nogduur on his throne. His followers were exiled from Duunhollow and the rest of the Silver Kingdom's territories.
The Ashbight Clan dug deeper into the earth to create their own kingdoms and holds, content to live in isolation away from what they say as a sick man's kingdom. The remnants of the Ashbight clan became the deep-dwarves.