phaaf_glien! Welcome, friend! We were great mates back on the Wizards forum, debating various Dark Sun topics and points of canon with the forum dwellers. On to the topic at hand!
Luckily, we have the Beyond the Prism Pentad sourcebook which was written to wrap up any unanswered questions and it surely answers your question. Oops. No, it turns out it doesn’t answer this question or many others, which is why I dislike that supplement.
What really happened? Troy Denning wrote 5 very interesting books about the Dark Sun setting but he left a ton of unfinished business. The Lord Mariner should still be out there. Ur-Draxa is can still be rebuilt. According to the Valley of Dust and Fire sourcebook, which I definitely believe over the Prism Pentad supplement, killing the Dragon and making him stay dead is no easy thing.
For my campaign or headcanon, I don’t do the dead Sorcerer Monarchs. Then what the heck happened during the Prism Pentad books? My personal fix for the the story of the novels if you want to make it an event that happened is to sidestep the consequences of those events.
The Sorcerer Monarchs are wary of Rajaat and also of each other. Once they realized that Rajaat was able to break some bonds of his prison and affect Athas, they took all precautions to defend themselves. Starting at Free Year 10 , none of the Sorcerer Monarch’s encountered by the protagonists of the novels are the real deal. The real SMs are holed up in extra-dimensional “panic rooms” because they fear a one-hit kill by Rajaat.
From the timeline, FY 10 -
Sadira kills Abalach-Re with the broken tip of the Scourge of Rkard on the Ivory Plain. The sorcerer-queen’s body is completely consumed by a black ooze leaking from the broken tip.
Sure, but that Abalach-Re was a simulacrum in my personal canon. The rest of the events also took place, with Tec’s simulacrum getting its head crushed, and Andropinis’ simulacrum being confined to the Black, and the Dragon being “killed” (again, a simulacrum).
So the story arc happens, but the consequences are different. We have the Tyr storms. We have Tithian imprisoned with Rajaat. But none of the SMs are dead, and life goes on. All of the SMs, when they think the others aren’t looking, attempt to recover the Dark Lens from the lake of lava. But its gone. Where did it go? That’s a mystery.
That basically resets the campaign to where it was right at the start. That’s IF you want to the Rajaat and cleansing wars route. I am a first box set originalist, so I prefer the mystery of Athas’ history. Rajaat is easy to refluff as an Elder Evil and nothing to do with cleansing wars.