Helagenn is a subterranean desert of the Menortamon Region. It was created in the Creation War (1486 DE - 8777 DE) by an earth elemental workforce. They used a cluster of sonic devices, blasting the area's rock to sand and dust. This project, small on a world scale, was one of many primordial projects that sought to undo Creation.
Today, the devices gone, the desert remains, a cold and dark place with primordial relics and other dangers left over from when the primordials used this area to test their machines of destruction.