The planet of Gor is several millenia old.
The Priest-Kings, that alien race native to the planet of Gor, have not explained why their world was moved from another solar system to that which Earth occupies.
Whatever the reason for the move, it’s certainly reasonable to assume this task in itself spanned millenia in planning. Tarl’s father, Matthew, in the indoctrination of Tarl upon his new home, explains that the Priest-Kings had moved the planet many times. Matthew refers to Gor as the counter-earth, following the same orbital path of Earth, yet remaining “behind” the sun in such a way so that would never be visible to the destructive force known as humans on her sister planet — Earth.
Casting much doubt on the whole probability of moving an entire planet without it disrupting life, both on the planet moved, but others as well, Tarl considers another thought — that Gor was always present in its current location, but hidden by a shield. Tarl discovers, that among humankind on Gor, this is considered the Theory of the Priest King Shield.
The planet of Gor is smaller than that of Earth and like Earth, is also a spheroid. Gravity on Gor is much lighter than that on Earth. Tarl eludes that it’s due to the smaller size of the planet and its orbital position, but we learn in the novels that this, in fact, is because the Priest-Kings have manipulated the gravity to allow life. John Norman speculates then that the people would be stronger and be able to accomplish superhuman feats in this altered gravitational state. Hence the strong males of Gor.
Another large difference between Gor and Earth, are their satellite moons. While Earth has but one, Gor has three moons; two large and one small, known as the Prison Moon. We are never explained the significance of this.
Gor bears many similarities to Earth, with much of the same general geological and ecological makeup, differing only enough to have its own character and wealth of indigenous organisms. With the move of the planet, likely some of the vegetation, if any, that were native before the move may not have survived the journey; or perhaps the Priest-Kings’ biologists manipulated the plantlife in order to ensure their survival. While some of the plant and animal life is similar to what is found on Earth, this was surely due to the arrival of man on the planet; said creatures necessitating the survival of humankind.
Many of the plants found on Gor are unknown to Earth; perhaps some originating on Earth, but adapting to the strange, new gravity of Gor, and the harshness of the world itself.
The arrival of man brought them a new animal to experiment on, which they did; the Muls Al-Ka and Ba-Ta are prime examples of the experiment of genetic mutation and manipulations. Another is the ancient mankind of some world perhaps not even of earth, that were raised to be the carriers of the precious Gur. The Priest-Kings filled their vivaria with humankind, releasing them to the planet which serves as a large-scale vivaria. To the Priest-Kings, humankind are but low animals, however it is explained by Misk, that the Priest-Kings brought men of Earth to Gor because they found them to be an interesting species. It was determined then, that humans would kill off their own species, and therefore, to rationalize their voyages of abductions, the Priest-Kings stepped in and placed various specimens of humans, as well as other species of many world, upon this new world to protect these species from total extinction.
Certain that mankind harbors self-destructive tendencies, the Priest-Kings became gods in the sense that they held the controls to the technological growth of man, that their mistakes on Earth are not repeated. Therefore, advanced technologies in areas such as weaponry is kept to a simpler level.
Failed experiments? Certainly, and with little thought the Priest-Kings would terminate the existence of such. Some were evaporated to dust; others ended up in dissection chambers for their corpse to be studied. Intervention within the more political level, included using agents, such as the clueless Tarl Cabot, to help bring a city to its ruination, but at other times, upon their occasional whim, the Priest-Kings would destroy a city to manipulate their own needs (such as what happened to Ko-ro-ba), or simply as a statement to mankind that they were growing too fast and too bold, or simply to remind them that they should remain humble before their gods.
Gor is a planet with much the same climate found on Earth. Again, this “official” site claimed the weather as being especially harsh. Rather, it is less harsh than that of Earth, although there are the various regions of harsh climates, as even on Earth itself, i.e., the polar caps, the desert lands and so forth. As on Earth, Gor promises its rainy seasons, its thunderstorms and sand storms, the winter snows.
Gor is a planet that is booming with natural beauty that could well surpass the natural beauties of earth. Left for the most part unexploited and unpolluted by mankind inhabiting the planet, kept in check the by Priest-Kings who brought them there to experiment with and study. The air clean, the skies and waters are clear of toxins such as smog. Mankind revels in the beauty of nature and considers the land and sky sacred.
Source material: the annals of gor