It is called Dirthavaren (the promise) in elvish, and is located in the Dales. The Exalted Plains is a grassland region with a myriad of abandoned forts.
Seven hundred years ago the elven nation fell on these very fields. The elven army was defeated by the human Chantry, defending their land to the last breath.
The Exalted Plains are now a contested battlefield in the Orlesian Civil War. As the Veil tears throughout Thedas, the spirits stir beyond the veil to possess the dead.