Region of Eternal Night
The Region of Eternal Night is a part of Orbis near the south pole that sees near eternal darkness. Very few, if any, of the inhabitants of Orbis know the cause of this darkness.
The region is inhabited by all sorts of creatures, most of them unsavoury. Drow and duergar reside here in substantial numbers, but nobody knows for sure what else can be found in the depths of the Eternal Night. Neveretheless, rumours of the terrors that can be found amid the darkness abound.
Though this is not known by the inhabitants of the world, the Region of Eternal Night is the result of an unusual astronomical phenomenon. Orbis's axis of rotation as it orbits its star is tilted, resulting in one hemisphere receiving more light than the other. However, at the same time, the axis itself rotates with a period the same as Orbis's orbital period. This results in an eternal summer for the northern hemisphere, and an eternal winter in the south.