From the introduction:
"This is the second product in the "Portals" series. The first product in the series, Portals of Torsh, deals with a world in which mammals never evolved and the primary inhabitants are the reptilian Lizard Men. This product details a section of a completely different world. One where the native animals have iron teeth and a strange resistance to the powers of magic.
Both of these products can be used as independent campaigns but have been especially designed to link up with an ongoing Advanced Dungeons & Dragons campaign through a limited number of teleport doors or portals (as they will be called in this booklet). It is no secret that many, if not most, Judges use the published playing aids as special environments which can be entered only through portals. This series of products has been designed to be especially suited to that sort of adaptation.
One final point: each of the "portals" projects deals only with a small portion of the world. You should be aware that Judges Guild has no intention to publish additional materials on any of the "Portals" worlds. You should therefore feel free to do whatever you wish with the rest of these worlds without fear of future contradiction by Judges guild."