Subterraria

Subterreria is a unique biome and realm in Soldaana, lying beneath its surface. It is an extensive system of tunnels, caves, and underground villages and metropolises that lie under Mirrin, Gallun, and Haltoss proper. As this land is removed from the natural light of the sun, much of the flora and fauna has adapted quite drastically to the gloomy underdark. This realm thrives on ingenuity of its people and use of the resources around them as the deep earth of the continent contains many gems, precious metals, ores, and the highly utilitarian and profitable - soul gems. For many years, the above and under sides of Soldaana's peoples were unaware of each others existence and contact was tumultuous at first. However, trade, business, peace, and more has been brokered since and the seat of power that facilitates this all is in the capitol dwarven fortress city of Fan-Gox-Uhl. Subterraria has a large presence of dwarves (Duergar), gnomes (deep gnomes), and elves (Drow).
This underground region of Soldaana is said to have been the original sphere of Fangor whose mantle of power and rule was based out of Fan-Gox-Uhl.