The Dragonvault, once called Mal'Gazar, was originally a great fortress from which Maligor ruled the realm of Taurech, during the Godstrife Era.
Within these dark walls, the Vorgar Lords plotted the enslavement of all the races of Tarn. Many Fae were subjugated by the Vorgar Lords. Some came willingly, pledging their souls in exchange for forbidden knowledge. The dark offspring of Vorgar and their Fae consorts were Ettins, the Trollfolk, and the Dragons. More monsters were sired later, such as the Vampires.
The world was plunged into chaos and violence, until the Eldrin and the Avalar joined forces and besieged Mal'Gazar at long last. Maligor was slain, and the rest of the Vorgar Lords bound in magical chains, in the deepest pits of the Netherworld. The spawn of the Vorgar who were not slain in the battle then fled into dark places.
Long years passed, and those Dragons which had not been destroyed multiplied slowly. By the time of the Dominion Era, their numbers had replenished, and many of them returned to Mal'Gazar, hoarding great wealth in the accursed halls where their fathers once ruled. Word spread, and this place became known as the Dragonvault. Many brave adventurers, righteous crusaders, and madmen travelled there. But few returned alive.