Thac is a large island continent west of the great mainland of Arinthar. It was once part of the mainland, before the Dragon-Titan War, when the world was shaken to its foundation and the continents were reformed, ending the Second Age. Thac is divided down the middle by the great Thertassel (Sky Wall in elvish) Mountains. Both sides of the continent are well populated, though land travel across the great mountains limits interaction between the two halves of the great island.
Eastern Thac is where the stories chronicled in the Heroes of Ravenford take place. Points of interest on the eastern side of the continent include the capital city of Lymeridia, the gnomish city of Llos to the north, the elven city of Kai-Arborus situated in the great forest of Ruanaiaith, the city of Dunwynn along the north eastcoast, the city of Penwick along the southeast coast, and the winding Korlokesel Mountain range.