Aulivar
In a time before time was counted by man, Ulei'Var was a battleground between gods and masters of the extant dimensions. Creatures of fire, good, evil, chaos and order battled incessantly over the material plane, nearly destroying the fledgling mortal races. Elves, dwarves, and Humans came together, and separated the material plane from the rest, ripping the planar terminus away from the entities vying for control.
Thousands of years ago, the last war ended. The last of the demonic creatures trapped in Ulei'Var when the worlds were separated was struck down, and the final great black spire fell deep into the earth. The few remaining angels, and other Goodly extraplanar creatures helped the mortal races seal their dark minions into the dark caverns deep below Ulei'Var, and departed willingly to their home planes, finally giving the mortal races an opportunity to move forward alone, unguided, and without interference... Mostly.
Few alive now remember those times. Kingdoms have risen and fallen, evil has reared its head and been struck down. The world has churned on, with the mortal races advancing in both magic and technology at a startling rate. The dwarves, forgetting the horrors of the past, continue to delve deeper, as the elves lose themselves in their woodland realms. Humans charge forward, unhindered by long life, while the mysterious Toraion, far across the sea, worship their strange god, and keep their secret ways.
In this time of great advancement, some would undo the great works of their ancient forebears. Some seek to reopen the great ethereal wall separating the plans, inviting their masters back into Ulei'Var, to claim their rightful place of domination. Others, long lingering since the Separation, desire to keep such gates closed, so that they can dominate the world as they see fit.