Hundreds. But it's not always large areas like the parts of Middle-Earth that are here, or like the vast tracts of the gnarly ground of the Disc that makes up much of the wild country. Sometimes it's as simple as a small town or city that's been transplanted here.

Still, overall, there are hundreds of worlds represented in some way in the Wilderlands, and in all of them no one seems to have the faintest idea what disaster caused all this.