Three thousand years ago, when Lolth and the drow were warring against Corellon, a large number of elves swore neutrality in the conflict and hid themselves in the Feywild in order to escape the chaos. For reasons that have long since been forgotten, the Feywild became disjoined from the material plane and all connection between the two was severed, trapping all of its inhabitants - including the goddess Sehanine Moonbow. The elves that remained in the Feywild were affected by the energies there, and over the course of the millennia they gradually transformed into an entirely separate race from their elven cousins. They reemerged back into Syra when the Feywild was reconnected with the Material Plane following the Deity War.
Most eladrin belong to one of the five Fey Courts: the Summer Court, the Winter Court, the Wild Court, the Court of Coral, and the Gloaming Court. Social statuses tend to be rigidly defined within their cities, and nobles are afforded a significant degree of power and prestige. Most eladrin of any social status regard themselves as being better than mortals, though some have chosen - for various reasons - to spend much of their time in the Material Plane.