The Pahn Soo Mountains are what the two components of the World Above Nehrahn are referred to.  There are technically two components to the continent: the Pahn Soo Mountains and the Plains of Dust, with the mountains surrounding the plains.  The entire continent is often referred to as the Pahn Soo Mountains by the denizens of the world.  The nine Clans of the Cave Elves dwell in the caves of the mountains and the upper-most caverns under the world's surface.