Eberron's Founding

Founding

The world of Eberron was founded, as the outcome of a war between three great dragons of the cosmos.

In the mythic past, the world was one and the Progenitor Dragons, the first and greatest of dragon-kind, ruled all. The three most powerful (Siberys, Eberron, and Khyber) discovered (or created) the Draconic Prophecy. Khyber and Siberys disagreed over the Prophecy and battled with one another. Khyber was victorious over Siberys, and sought to take control of the Prophecy, only to be attacked by Eberron. Eberron wrapped her coils about Khyber, trapping the evil wyrm.
  In the end, Siberys' shattered body became the Dragon Above - the glowing ring that surrounds the world. Khyber, still trapped in Eberron's coils, became the Dragon Below and the source for all great evils. Eberron healed the World Between by becoming one with it. Siberys called forth the next generation of dragons, Eberron created all manner of other living things, and Khyber spat out the fiends.

Credit: https://eberron.fandom.com/wiki/Eberron_Timeline