A similar but distinctly different universe.
Mists of Antiquity
The Faerie races lived before the advent of mankind.
The evil Faerie races, known as Demons, were imprisoned in a mystical prison with the sentient tree, the Ellcrys, as its warden, gate, and key. The Elves, the major good Faerie race, tended the Ellcrys. Most other Faerie races eventually passed into oblivion.
Advent of mankind
The elves kept their presence secret from this new race; eventually their territory was limited to a small area around the Ellcrys, what they called the Cintra, in what we call Oregon.
Man lived by science, knowing no magic save for a select few individuals; most others disbelieved in magic or even the possibility of things unseen.
Spurred on by evil itself, known as the Void, demons came to be formed from humans. These demons paved the way for the destruction of humanity in nuclear fire. Then, they began mopping up the survivors.
A small band of humans, elves, and mutants found refuge in a protected valley. A magical barrier was placed over this valley.
Age of Magic
Fifteen hundred years after the final volley of the great war which plunged the world into nuclear winter, a new world has arisen in which magic is practiced by all races. Mutant races have taken on the names of ancient races of lore, both mortal and faerie.