The Obsidian Basin of Equinox

Overview

As the northern glaciers begin their lethal winter expansion, the nomadic tribes of the Fahill Nations complete their Southern Transit to the Equinox. Positioned at the base of the mountain passes leading to Scieles, this city is a marvel of thermal insulation and seasonal urban planning. During the summer months, the basin is a blistering, arid wasteland of sun-baked stone; however, as the winter rains arrive, it transforms into a lush, pressurized oasis.

Architecture and Thermal Regulation

The city is constructed primarily from the region's dark, volcanic rock, which serves as a massive heat sink.

• The Sunken Plazas: To protect inhabitants from the biting mountain winds, the majority of the residential sectors are built directly into deep, terraced depressions. This utilizes the natural geothermal warmth of the foothills while providing a physical barrier against the southern gales.
• The Rain-Catchers: Vast, decorative stone funnels are positioned throughout the city's upper rim. During the winter storms, these collect and distribute rainwater into a complex network of internal aqueducts, fueling the city's brief but intense agricultural cycle.
• The Summer Stasis: When the heat becomes intolerable, the tribes depart for the north. The city is 'sealed' using massive obsidian sluice gates to prevent sand and heat damage, leaving the stone halls to cool in silence until the next thermal shift.

Economy and Diplomacy

The Equinox serves as the singular legal funnel for interaction between the subterranean logic of the Fahill and the specialized markets of Scieles.

• The High-Pass Markets: These vaulted chambers stay at a constant temperature year-round due to their depth. Here, boreal timbers and rare 'Cold-Forged' minerals are traded for the mechanical tools and Arcane Science glasswork required to survive the northern thaws.
• The Scielian Gate: A heavily fortified mountain tunnel that connects the Equinox to the southern continent. Access is strictly regulated by the Thermal Overseers, ensuring that no southern 'divine artifacts' or 'cultural contaminants' leak into the nomadic population.

Academic Classification

Aillutian scholars categorize the Obsidian Basin not as a city, but as a 'Thermal Battery.' They argue the architecture is a physical manifestation of the inhabitants' mathematical survival instinct. While local oral histories speak of the 'Breath of the Mountain' providing heat, Academic Archives dismiss this as a primitive misunderstanding of the region's localized geothermal venting and atmospheric pressure gradients.