The Water Margin
The bloated, red sun of Athas beats down with terrible intensity. By day, the Tablelands are scorched desert. At night, they are frozen wastelands. People survive only by avoiding the worst excesses of the heat and seeking shelter from the sand.
During the day, temperatures routinely rise to 130 degrees F. At such times, most sensible people remain out of the sun; wealthy nobles employ slaves to fan them, while luckless citizens huddle under the shade of crumbling walls. Even slaves often have a brief respite at such times, simply because the heat is so intolerable that overseers must rest as well.
At night, the desert quickly gives up its heat. Two hours after sunset, the temperature plummets. Although there is not enough humidity for ice to form, breath mists over and the cold can kill anyone foolish enough to be unprotected or to lay directly against the earth. The twin moons, Ral and Guthay, provide dim light but no warmth.
Water is the most precious commodity of the desert. The city-states survive only because they have reserves of water in deep aquifers tapped by wells, or mud flats from which they can filter water. Running water on the surface is almost unheard of, while rainfall happens no more than once per year in most parts of the Tablelands.
Small towns and villages dot the Tablelands, and most have their own source of water — generally a single well. If a well should dry up, so too does the settlement.
The brutal environment breeds creatures and plants that are tough enough to survive such climates. Domestic mammals are long since gone from the surface of Athas — lizards, insects, and birds are the beasts of labor and flocks for herdsmen. Creatures that can survive the rigors of the desert are often extremely tough, dangerous, and aggressive, with poison, natural psionic abilities, tough or shell-like hides and fearsome natural weapons.
The searing heat makes agriculture a difficult proposition. Most of the city-states use irrigation or mud flats to grow crops where possible. Even so, famine is always a bad harvest away, and in lean years the sorcerer-kings do not hesitate to enslave hungry mouths and throw them into gladiatorial battles. A given city-state generally cultivates three or four different grains or vegetables, and herdsmen of the Tablelands have only a like number of animals suitable for their domestication. As a result, dietary variety is very slim, except for nobles who can afford rare delicacies such as fruit.
The scarcity of water and food means that landowners will not hesitate to work slaves to death rather than exhaust their meager supplies to feed such unfortunates.