Dark Sun: The Scorched World of Athas
Primordials are extremely powerful creatures of the Elemental Chaos. Myth says that it was the primordials who first shaped the world from Chaos.
In the Dawn War, the primordials fought the gods and defeated them, effectively ending their influence on Athas.
According to the research done in the library of Evan Moreau, in some realms, the primordials were defeated by the gods and their influence became greatly diminished.