In Burroughs' concept, the Earth is a hollow shell with Pellucidar as the internal surface of that shell. Pellucidar is accessible to the surface world via a polar opening allowing passage between the inner and outer worlds. Through that hole a rigid airship visits in the third book of the series. Although the inner surface of the Earth has an absolute smaller area than the outer, Pellucidar actually has a greater land area, as its continents mirror the surface world's oceans and its oceans mirror the surface continents.

A peculiarity of Pellucidar's geography is that due to the concave curvature of its surface there is no horizon; the further distant something is, the higher it appears to be, until it is finally lost in the atmospheric haze.

Pellucidar is lit by a miniature sun suspended at the center of the hollow sphere, so it is perpetually overhead wherever one is in Pellucidar. The sole exception is the region directly under a tiny geostationary moon of the internal sun; that region as a result is under a perpetual eclipse and is known as the Land of Awful Shadow. This moon has its own plant life and (presumably) animal life, and hence either has its own atmosphere or shares that of Pellucidar. The miniature sun never changes in brightness, and never sets; so with no night or seasonal progression, the natives have little concept of time. The events of the series suggest that time is elastic, passing at different rates in different areas of Pellucidar and varying even in single locales.

[edit] Culture

Pellucidar is populated by primitive people and prehistoric creatures, notably dinosaurs. The region in which Innes and Perry initially find themselves is ruled by the cities of the Mahars, intelligent flying reptiles resembling pterosaurs with dangerous psychic powers, who keep the local tribelets of Stone Age human beings in subjugation. Innes and Perry eventually unite the tribes to overthrow the Mahars' domain and establish a human "Empire of Pellucidar" in its place.

While the Mahars are the dominant species in the Pellucidar novels, they seem confined to their handful of cities. Before their overthrow they use the Sagoths, a race of gorilla-men who speak the same language as Tarzan's apes, to enforce their rule over the human tribes within the area which they rule. Though Burrough's novels suggest that the Mahar realm is limited to one relatively small area of the inner world, John Eric Holmes' authorized sequel Mahars of Pellucidar indicates there are other areas of Mahar domination.

Within and outside the Mahars' domain are scattered independent human cultures, most of them at the stone age level of development. Technically more advanced exceptions include the Korsars (corsairs), a maritime raiding society descended from surface-world pirates, and the Xexots, an indigenous Bronze Age civilization. All or most of the human inhabitants of Pellucidar share a common world-wide language.

Pellucidar also harbors enclaves of various nonhuman or semi-human races. There are:

* The Sagoths.
* The Ape Men are ape-like, black with prehensile tail, arboreal.
* The Sabertooth Men are ape-like, black with prehensile tail, cannibals with dagger-like tusks.
* The Brute-Men are peaceful gorilla-like farmers, sometimes called "Gorilla-Sheep" for the sheep-like appearance of their faces.
* The Azarians, primitive man-eating giants.
* The Ganaks, a race of horned bison men.
* The Horibs, ferocious dinosaur-riding reptile men.
* Two subterranean races are:-
o The Coripies or buried people, short eyeless carrion eaters
o The Gorbuses, cannibalistic albinos who are apparently resurrected surface-world murderers.

Mahars and Sagoths will be in Pellucidar

The Ape Men would probably be seen as too offensive and will not be in the mod

The Brute-Men, Azarians, Ganaks and Horibs may all make appearances.

The Coripies and The Gorbuses have been combined into one race with two distinct branches. These will be the subterranean Amiocops, the two center cities inside the caves leading to Pellucidar will house the dark and light versions of these people. They may refer to themselves as Coripies or Gorbuses or they may worship god of those names and call themselves followers of Coripi or Gorbus.