It is said that the Eld were here before and returned after the time of the Destroyers. Forseeing a great cataclysm, the Eld had travelled to a different plane of existence and carried ancient knowledge (even more ancient than the Destroyers).
The Eld are said to have returned to the World many thousands of years after it’s destruction at the hands of the Destroyers. Seeing the World uninhabitable, the Eld constructed vast cities underground in the Northern lands where they worked to heal the damage to the World caused by the Destroyers. It is unknown if their attempts succeeded or not. It is unclear if the current life is the result of the Eld’s attempts at healing the World.