You get to this area after getting out of the Dead Nations Catacombs. There are big white dinosaur-looking trocopohaca, as well as lots of other creatures to kill here. The ghouls are expanding their feeding areas but leave you alone.

To the far southeast you find the sphere you've been seeking on a body - take this back to Pharod to continue the story along. You find a flask of clean water, which you bring back to Glyve. You also find a sealed path, which only you can enter.

Be warned, you're going to die a few times in this tomb area. You keep resurrecting right in there, so don't worry much about it. You go into a central area and one by one go north, south, and west as you gather up the portal keys. Finally, written around the central area is the first journal of yours you find. It tells that you shouldn't trust the skull, and tells other things about your past. Push each panel in and grab the last tomb key, to return out to your companions. Have them rejoin your party.

Planescape Torment Walkthrough
Walkthrough Master Index