Under the description of the Elo Chief, Aiwass seemed to fall into a hallucination.
There were raging flames that could not be extinguished.
The habitable oases were destroyed, food was burned, residences were torched.
People, with nowhere to settle, were constantly driven by these demonic flames to new regions. And in those new settlements, a fresh blaze would erupt... People were burned and died, trampled and crushed in panicked flight.
At its core, it was because the easiest resource to extinguish fires—water—was a regulated resource unattainable by ordinary people in any city of Parthia. It is "liquid life" more precious than wealth.
No one would be willing to use their own water to put out fires, not to mention a person's water is far from enough to douse the flames.
As for the Transcendents...