Aeron

A world floating in the Aethar, touched by a handful of gods and fraught with much danger. 

During the creation of the world a powerful artifact, "The Soulforge" was created and used by lost gods to build Aeron from the Aether itself. The Soulforge used power from the gods themselves to create and arrange all the planets areas. Then the gods vanished, few know of them let alone what happened to them. The very limited knowledge on this time frame seems to infer the gods eitehr left, died, or entered the Soulforge itself (willing or unwilling).

The first civilizations were lifted from the elements themselves and given Humanoid or other forms.
First came the Dragons, then the Giants, followed by the Dwarves and Elves. The outer planes already existed and the Bloodwar was in full swing already. Fiends and Celestials stayed out of mortal affairs, other than to occasionally recruit valuable assets to their side of the war.

Before them all however, there existed another race, no written text indicates who created them or where they came from exactly, but they ruled the world before Dragons and were somehow able to tap into the Soulforge itself to create their own servitor races. Their creations became Lizardfolk, Yuan'ti (Originally of Elven stock rather than Human, though they becamoe more Human-like ove rtime), and the various Naga species, just to name a few. They called themselves the Sarrukh and few still exist as the other races eventually stood as a unified front against them, driving them to flee to other dimensions or perish with some of their creations.