The dominant feature of the central Nocthean Caldera, Mount Nyx rises roughly 4,500 feet above the central rolling plains of the Caldera floor. A volcano in its own right, Mount Nyx last erupted at the end of the First Interregnum, at the dawn of the Age of Men and Gods. Since then the mountain has remained quiet, mostly due to the restraining influence of the Nocthean clergy who occupied the Caldera throughout the 3rd Age. It became the center of the Hungering Frost and the lair of the dragon Sorrow-wing until her defeat at the hands of the Traveller adventuring party and the Frost's collapse in late 211 AC. Only recently, with the retreat of the ice-cap, has the whole complex become accessible. Retaking it and rebuilding it is a major driving desire for the Church of Night Reborn and its clergy; this goal is contested by the Wyrmhold Dynasty.
Mount Nyx in the 3rd Age
During the 3rd age, the Nocthean Caldera was home to the isolationist culture known as the Noctheans. Devout monotheistic worshipers of the goddess of night, mystery, secrets, and magic (specifically relating to magic items), Nocthis, the Noctheans were a unique ethnic group easily identified by their ice-pale skin that never tanned or burned in the sunlight and long, straight, night-black hair. They called this "night's blessing". Matriarchal and theocratic, they were ruled by the priestesses of Nocthis from their temple-fortress buried inside of Mount Nyx, located at the heart of the Caldera. Around the mountain and on its slopes they built the City of Night, Nykopis. Few outsiders ever saw more than the outskirts, as the Noctheans were not welcoming of outsiders.
Their isolation on the high plateau of the Caldera did not mean that Noctheans were unknown outside the Caldera. They routinely sent teams, led by a battle-priestess, to recover artifacts of power that threatened other areas. These they brought back to the temple, where they were sequestered and sealed away for eternity. To many citizens of the Western Empire (and later the successor states), the Noctheans were a bothersome group--ready to interfere in others' business but loath to allow interference in their own.
Yet all through this time, the Western Empire never attempted to conquer the Caldera. In fact, they took strong measures to prevent any interference. In return for this hands-off relationship, the Noctheans paid a nominal tribute of one daughter per generation as a bride for the Emperor at his ascension. This Bride of Night didn't stay in Imperial Center, however--after the wedding she returned home to her people and acted as ambassador for the Empire there.
Why was the Empire (normally so grasping and expansionist) so hands-off with the Noctheans? Some believe that Mount Nyx holds the answer. For it is a fact that the oldest records, dating back to pre-Empire times, state that the kami of Mount Nyx is Kubi, a fearsome, destructive, fox-tailed beast of lava and hatred, prone to sudden and violent eruptions that would darken the sky for days all across the western side of Noefra. Yet the last eruption dates from before the start of the Nocthean residence at Mount Nyx. Some believe that the ancient Noctheans discovered a way to harness and contain Kubi; to threaten them would be to threaten a re-awakening of Kubi and his world-shaking anger.
Whatever the reason, the Noctheans lived a simple life throughout the 3rd age. Very few arcanists rose from among them and they were known not to use magic items themselves--they only acquired them to keep them out of "the wrong hands." This pattern continued even during the War of Empire's Fall. During this time they granted the newly-created dragonborn people a home at the east edge of the Caldera, a region that became known as Wyrmhold. This situation continued until the Cataclysm, although the Noctheans progressively withdrew from the rest of the world.
Throughout this whole age, the Noctheans continued to tunnel and mine out the inside of the mountain. Several key areas:
- The Burning Heart. Deep within the mountain is where Kubi is contained, along with a Lava Nexus. The elemental output of that nexus is funneled up and serves to power and heat the rest of Nykopis as well as the vaults and portals higher up.
- The Nighthold. Above the Burning Heart but still beneath the level of the outside ground, the Nighthold contains the relic vaults as well as the research, training, administrative, and record-keeping areas of the retrieval teams, and the portals (both local and interplanar) that the teams used to facilitate their divine mission.
- The Temple of Night. Located at ground level, this was the heart of Nocthean government and culture. Here they held their rituals (forbidden to outsiders) as well as had councils and trials and pronounced new legislation.
- Habitation warrens. Located in the cone of the mountain, this is where the bulk of the ranking priestesses and their families lived. Multiple smaller temple-caves also dotted the interior of the mountain.
- The Observatory. Located in the caldera of the mountain, this was a sacred space for the highest-ranked priestesses to observe the night sky and seek answers from their goddess.
Mount Nyx after the Cataclysm
The Noctheans left the Caldera after the Cataclysm and the death of their goddess (along with all the other gods). Their descendants, the Byssians, never speak of this time except as "the Exodus". No one (except likely the monks of the Home of the Elements) know why they did, but the fact of their departure is incontrovertable. But whatever the reason, they left the mountain and its precious contents behind. And still the mountain (and Kubi) slept. Wyrmhold still maintained their place on the edge of the Caldera, but was left alone.
Approximately 100 years later, a sudden frost sprang up. Coming, it seemed, from Mount Nyx, as if the mountain had erupted in ice and snow instead of fire and lava, it swept over the entire Caldera and down the pass to the north as a glacier. Out of that ice and snow came The Hungering Frost, implacable, inscrutable, and deadly. It drove the dragonborn off the Caldera; only extreme sacrifice and constant vigilance allowed them to maintain a hold on the only pass to the east down toward Safehold.