Tyar-Besil was the ancient fortress-city of the shield dwarf kingdom of Besilmer, built under the Sumber Hills in the Dessarin Valley. It was eventually overrun by hordes of orcs, trolls, and giants. The fortress-city was later used as a base for the Cult of Elemental Evil in 1491 DR. After the cult's defeat, dwarves began to reclaim the ancient site.