Thunderholme was a dwarven kingdom in the region known as the Thunder Peaks. Dwarven legends spoke of the city as favored by Dumathoin, the Keeper of Secrets Under the Mountain, and that it was home to the noblest miners and finest metalsmiths in the Realms. It was also said that its vaults were emptied in a day, when Dumathoin swept his chosen away to live in paradise with him. The truth however was far more horrible and tragic. The realm fell into decline when its king and heir were assassinated, and then was finally conquered by Aurgloroasa, a powerful shadow dragon, in 1054 DR.
In 616 DR, scouts from Thunderholme noted the arrival of a powerful and potentially dangerous dragon called Aurgloroasa in the region but the dwarves chose to do nothing about it. This choice would eventually lead to their doom.
In 989 DR, miners from Thunderholme accidentally expanded their delves into the lair of Aurgloroasa, rousing her from her centuries-long sleep. She immediately despatched the miners and caved in their tunnel to make it appear as an accident. but the damage had been done. She became interested in Thunderholme's operations and observed the dwarves via divination magic and spies summoned from the Plane of Shadow.
In 1001 DR, Aurgloroasa began to whisper dark promises in the ear of the High Old One, the high priest of Dumathoin, Dagan, son of Belgin, Blood of Jangarak, goading his ambition and desires. He became obsessed with death, naming the voice "The Sibilant Shade", a title that pleased Aurgloroasa greatly. Her advice fueled his obsession and he gradually rose to power and prominence, becoming second only to King Emerlin III himself.
In 1034 DR, King Emerlin III died mysteriously in his sleep, leaving no heir as his son had recently disappeared on a trade mission to the Sembian city of Selgaunt. Having no other option, Dagan of Dumathoin was named royal regent. One of his first orders was to commission a grand temple of Dumathoin, a task that would gradually grow to obsession.
In 1054 DR, the Priest Regent unveiled his magnificent temple in a grand dedication ceremony attended by every dwarf in the city. He then shocked the population by dedicating his new temple to Null and not Dumathoin, naming it the Necropolis of the Wyrm and then summoned Aurgloroasa, whom he believed to be his god's avatar. The dragon then proceeded to kill all but about thirty dwarves, many of who were later hunted down and slain in the following weeks.
By the 14th century, the halls lay dead and empty, the hammers and forge fires silent. The only occupants were the restless dead, the countless hordes of dwarven nobles, warriors, merchants, and commoners that wandered the halls as skeletons, ruled by their deathly queen, Aurgloroasa, "the Sibilant Shade".
Thunderholme was known to employ Dethek runestones to bypass wards and gain entry to the city. A runestone was a magical stone tablet carved with dwarven runes and used to open magically sealed or hidden doors. When the city fell, Aurgloroasa may have slain every dwarf that escaped but did not recover every runestone. Four runestones surfaced in the 14th century, two in the hands of the Cult of the Dragon, one in the hands of adventurers, and lastly, one in the vault of an adventuring club in Harrowdale.
- Dale Donovan (January 1998). Cult of the Dragon. (TSR, Inc), p. 38. ISBN 0-7869-0709-6.
- Dale Donovan (January 1998). Cult of the Dragon. (TSR, Inc), pp. 38–40. ISBN 0-7869-0709-6.
- Dale Donovan (January 1998). Cult of the Dragon. (TSR, Inc), p. 40. ISBN 0-7869-0709-6.
- Dale Donovan (January 1998). Cult of the Dragon. (TSR, Inc), p. 39. ISBN 0-7869-0709-6.
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Shanatar (Barakuir • Drakkalor • Holorarar • Korolnor • Torglor • Ultoksamrin • Xothaerin) • Thunderholme