Progenitor Dragons

The common creation myth of Eberron holds that the three great sibling progenitor dragons (Siberys, Khyber, and Eberron) formed not only much of the universe, but also the planar system, and were the authors of the Draconic Prophecy. According to myth, Khyber betrayed her brethren and murdered Siberys. Eberron then used her own body to bind and trap Khyber in the depths of the world. Siberys is called "the Dragon Above," Eberron "the Dragon Between," and Khyber "the Dragon Below." The body of Siberys is said to have formed the ring of stars seen in the heavens, while Eberron's body became the surface world, and Khyber's became the underground realm of the same name.