The Ferian Gap is a mountain pass that lies between the Ruhnn Mountains and the White Fang Mountains. It's a deadly, blasted bit of land, and one of the few passes between the fertile lands of the east and the Western Wastes.
Manon Blackbeak recalls making it through the passage just once. She describes it as a "snow-crusted labyrinth of caves and ravines." She traveled with the Thirteen and two other covens, and only the Thirteen made it out.
The Ferian Gap was where Erawan's soldiers bred and trained Wyverns as an aerial force.
During the war with Erawan the Ferian Gap was the location of about half of the host of Ironteeth Witches along with their Wyverns. The Ferian Gap is also where Erawan’s and Mother Blackbeak’s witch mirrors supposedly were.