The Realm of a Thousand Skeletons

A desolated kingdom found deep below the earth's surface. This kingdom is filled with a thousand volcanoes, thousands of sluggish rivers of lava, and a thousand skeletons. Humanity must save itself, for when all humans go extinct, they shall all plummet down to The Realm of a Thousand Skeletons, where they remain the dead creatures of the past.

I cannot believe it, when a large population of one single species die, they go to The Realm of a Thousand Skeletons!