The Ered Lithui, or Ash Mountains, were a mountain range that ran for many miles along the northern border of Mordor. Though they do not form any part of the stories of the First Age, they became much more important as Sauron occupied Mordor.

Barad-dûr, The Dark Tower, was built by Sauron at the end of the short spur that runs in a southerly direction from the main ridge of mountains.