Feywild

The Feywild, also known as Faerie, is a plane that exists as an "echo" of the Prime Material Plane. It is from here that the fey originate, giving the Feywild its name, and it is also a place of unusually potent magic. Much as in the Shadowfell the Feywild's geography is similar, though not entirely identical, to the geography of the Prime. Similarly, just as the geography is reminiscent of Toril's, so are its inhabitants and many creatures exist as fey "echoes" of the Prime creatures.

History
The Feywild, also known as the plane of Faerie, was created by the Primordials, beings of power comparable with the gods. Finding some things of the Prime too "bright" or too "dark," the Primordials split the Prime into three nearly identical worlds: the Plane of Shadow and the Feywild. For a time the Feywild was located in close proximity with the Prime and the inhabitants of both planes interacted regularly. It was during this time that the eladrin and other fey first immigrated to Abeir-Toril.

Later, likely due to the Sundering that created Evermeet, the Feywild slipped out and away from the Prime. Contact between the two planes ceased except through intermediaries or powerful arcanists and the plane was largely forgotten. This changed again, however, with the Spellplague. The destruction wrought by Mystra's death yanked the Feywild back into proximity, opening up new crossroads to the plane. Now that the barrier between these two planes is much thinner, the eladrin (who originated from the Feywild) discovered that their close bonds with that realm allow them to slip into and out of the Feywild.