The Flathead Mountains are a towering range in the Eastlands from north to south, forming the eastern border of the Frigid River Valley. Their tallest peak is Mount Foobia, reaching the top of the world. Beyond the mountains, the Fenshire Swamp extends to the edge of the world.
The Mountains contain the Enchanters' Retreat.
Dimwit Flathead had a hidden vault 7 miles under the Mountains, accessible by a chain of 63 secret teleport spells.