Dargrath's caverns

Dargrath's caverns was a systems of caves and tunnels located beneath the Earthspur Mountains. As the 14 century DR, they were the last remnant of the formerly-great hobgoblin realm of Haekrukkha. The caverns earned their name from Dargrath, the famed hobgoblin warlord who ruled the ancient long before the founding of Impiltur.

History
Just prior to the fall of Haekrukkha, Dargrath and loyal cabal of shamans fled the region that came to be known as the Uplands and ventured deep into the system of caves located beneath the Earthspurs. After their descent, they caved the walls in behind them and sealed the only route that led to the surface land.

Shortly before the Year of Lightning Storms, 1374 DR a group of miners broke into Dargrath's caverns as they were following a particularly abundant vein of silver ore. Within the caves they discovered several ancient alters, unusual pictograms and skeletal remains that led them to believe that mind flayers had taken over use of the subterranean tunnels.

In the following years several adventuring companies, such as Knights of the Elder Flame and the Loviataran Spiked Sisterhood, led expeditions into the caverns but were never heard from since. While the furthest depths of the tunnels had not been fully explored as of 1374 DR, sages continued to speculate about the secrets that remained therein.