I had ideas for adapting a dark sun “fan novel” called “New Breed” that never took off from like 2004’s ideas for the southern continent, ie a relatively untouched, hostile continent inhabited by a mutant race with lifeshaping, called “Fyanralas” - I found it while perusing old Dark Sun geocities remnants on wayback machine and liked the concept. It might have been the user “Ral of Tyr’s” site?
"Across the Silt sea, beyond the valley of dust and fire lies the ancient continent once known as Fyanralas . This verdant subtropical land survived the ravages of the Cleansing Wars due solely to the presence of one of Athas most ancient and deadly races the Rux. The Rux are a race as old as the Blue Age halfling’s and very little was known about this mysterious race. That was until the Wanderer ventured there… I thought my life was due to end, and I would be drawn into the gray. It had been over a week since the skimmers food stores had been depleted and out of the twenty five crew which set sail from Balic only twelve were left. Daranga the water priest was the only person keeping the rest of us alive with her undying devotion to her sacred element. The expedition had been traveling east for two score days and the mindbenders were working day and night using their own power and the psionic energy stored in the crystals which stood round the floaters pit to keep the skimmer moving. Then the lookout screamed with joy, almost dropping his King’s eye overboard. Land had been spotted on the horizon. The closer the skimmer got to the mainland, I was surprised to see a dense tropical forest growing up the steep hill sides. The silt was also getting more shallow and with every yard and eventually turned to mud and to the crews delight shallow muddy green water with plant life abundantly growing and almost grasping out at the hull of the Winged lady as if to welcome us to this new land. "
Likewise for the other continent’s names I wanted to recycle really old info from super early drafts of Secrets of the Dead Lands, like going back to the original Denning Manuscript. The very basic idea for the Descendants of the Chosen at Nagarvos was there, but were like 4 feuding families from different parts of Athas, including polar regions. Less the idea itself and more those names for continents and regions.
(Very) Tentative concepts (mostly just “plot hooks”)
-Fyanralas is the continent south of Remaan, and was never colonized by them for good reason- the native Nikaal of the continent, around since the Blue Age, also mastered lifeshaping- while not as advanced as the rhulisti, they had less qualms aboit altering themselves and now call themselves Rux. Fyanralas is the most untouched, vibrant continent on athas, even bearing a thin ring of ocean around it- this is mostly because the Rux have slaughtered anyone, Blue, Green, or Brown Age, who so much as step on their shores
Pyatha and the islands of Messenia and Seren- following of one of brax and bell’s only mentions of these continents, the “central continent”, Pyatha, was pretty much unhabitable to the Rebirth races but home to sizable populations of Kreen, Rhulisti, and Nikaal- and many, many giant bugs. Most kreen civilzation is centered around the heavily alkaline central sea, while most of Nikaal civilization proper is on the western end facing Remaan. The Remaans failed to colonize Pyatha but “uplifted” the Nikaal via kobold, pterran, and lizardfolk emmisaries, and the Nikaal are organized in a series of pseudo-Remaan “republics”
-Grank (Based on ideas from Brian Sanchez) Athas’ north pole, hone to a massive ancient rhulisti experiment with the planes and the most advanced remnants of their civilization (basically the halfling New World Order hiding in a bunker in Greenland)
Yutcha- Athas’ south pole
Note this is going off the Bell/Brax concept that in addition to the Kreen the Nikaal were another race native to Athas before/along with the Rhulisti, but likewise only semi-sapient at the time.