When the mortal creatures of Eberron dream, they project their minds to Dal Quor. The outer edge of the plane is ringed with the “dreamscapes” where these night-time fantasies play out. Within this ring, nightmarish psionic beings known as quori dwell. Dal Quor (and the quori) is subject to a cycle of implosions and renewals. The plane is periodically destroyed along with all its inhabitants to emerge in a different state of being/age. The current age is an age of darkness due to the fall of the giant civilization. The whole Quori/Kalashtar War is about halting or furthering the cycle, as this renewal would destroy all the current quori.
Forty thousand years before the “present” of the Eberron setting, the quori attempted to invade and conquer the Material Plane. The giant civilizations of Xen’drik managed to repel the invasion; in the process, their powerful magics displaced Dal Quor from its metaphysical orbit, causing it to become permanently remote from Eberron. Current theories suggest these past quori were in fact refugees from an unknown event in Dal Quor who were attacked by the giants, now all destroyed with the last shift of Dal Quor. Upon the discovery of the cycle by the quori, two factions emerged leading to the creation of the Kalashtar and the the Inspired. When the link between Dal Quor and the material plane was severed, the quori were forced to find another path to power in the Material Plane, one which culminated in the establishment of their rule as the Inspired – believed by their subjects to be incarnate gods – over the empire of Riedra on the continent of Sarlona and the efforts to bring Eberron and Dal Quor coterminous again.