Ribosians were a race of humanoids native to Ribos. Externally, they appeared identical to humans. They were a relatively primitive species, hence they were not aware that life existed off their planet.
The Ribosians had a vaguely medieval-European culture. Possibly ruled by some sort of monarchy, Ribosians had crown jewels which were guarded by Shrivenzales and Shrieves in a relic-room and were greatly revered. The Shrieves performed a ceremonial opening of the relic-room each day, where they gave thanks "for the dawn of a new day, and the retreat of the night, and the powers of darkness", and another locking it at night.
Ribos had an elliptical orbit around its sun and only two seasons: Icetime and Suntime. Each lasted approximately thirty-two Levithian years; the Ribosians believed the Ice Gods and Sun Gods were fighting for control of the world. The Ice Gods were believed to live in the catacombs beneath Shur, along with the dead.
They believed Ribos was flat and if they walked far enough they would fall off. They also believed the stars were ice crystals and there were no other planets. Binro the Heretic was tortured for suggesting otherwise. The Ribosians also believed in the Seeker, a woman who appeared to have clairvoyant powers. (TV: The Ribos Operation)
Though they generally used simple weaponry like spears, and had yet to invent the telescope, the Ribosians invented a type of cannon and used a type of currency called Opeks.