Bortresoye

Bortresoye was a planet located in the Divergent Universe. The planet was divided into a number of zones, with each zone containing vastly different environments and cultures. (AUDIO: The Last) The borders and spaces between the zones were occupied by the Interzone, and transit between the zones was carefully controlled by the Kro'ka. Some of the zones were fully aware of adjacent zones, while others were oblivious to their existence. (AUDIO: Scherzo, The Creed of the Kromon, The Next Life)

The Eighth Doctor and Charley Pollard arrived here when they were banished to the Divergent Universe, and spent many weeks crossing from zone to zone. (AUDIO: Zagreus, Faith Stealer)

Some of the zones included:
 * A zone taken from the planet Eutermes - inhabited by Eutermesans. The Eighth Doctor's companion C'rizz was from here.
 * A zone ruled by the Kromon. They frequently raided the Eutermesan zone for slave labor. (AUDIO: The Creed of the Kromon)
 * Light City - the zone of a short-lived species with eight limbs that practised frequent revision of its citizens' memories and personalities. (AUDIO: The Natural History of Fear)
 * A zone taken from the planet Setarus, which contained jungles and a sentient cave. (AUDIO: The Twilight Kingdom)
 * The Multihaven - a zone with hundreds of established religions, all occupying a vast city devoted to religious study. (AUDIO: Faith Stealer)

The planet also had its own territories, containing at least two societies locked in national rivalry. These two regarded themselves as the pinnacle of evolution, going so far as to abandon natural procreation for their species. (AUDIO: The Last)

History
The Divergent Universe had an unending cycle of birth, progress, death and rebirth lasting tens of thousands of years. The Divergence, a powerful race trapped in this universe when it was created by Rassilon, resolved to break the cycle and escape to our own universe. As part of the experimentation to this end, they constructed a mobile platform (a planet, really) where they could conduct evolutionary experiments. The planet carried its own cycle of death and rebirth, similar to the surrounding universe, but with a much higher frequency. (AUDIO: The Next Life)

The main society on the planet, ruled by the lady Exelsior, staged a nuclear war against its rival society, which led to the complete destruction of both societies. The planet then produced earthquakes, volcanoes and other disasters to cleanse the final living things off the planet, at which point the planet renewed itself, resurrecting all of its denizens with no memory of the previous destruction. (AUDIO: The Last)

It's unclear what effect, if any, the cycle of destruction and renewal had on the other zones on the planet.