The Dunen are vast mountain plateaux that run like a reversed L across Anasthias, carving it into three regions: Orror to the northwest, Harthera and Anarthis to the east, and Munatan to the south.

The Dun Jaen range runs north-south, separating Orror and Harthera, while the longer Dun Trisan runs east-west to separate Orror and Munatan.

Geographically these represent the heighest points in the world, formed in ages past by massive outventing of heat and gases deep within the planet's core. There are many long-extinct volcanic cones and precipitous valleys, but much of the summit, particularly in the southerly Dun Trisan, are relatively flat rocky plateaux.