Udûn (valley)
From Tolkien Gateway
Udûn was the deep valley in the northwest of Mordor, formed at the meeting of the Ered Lithui and the Ephel Dúath, whose northern entrance was guarded by the Morannon.
Udûn was the deep valley in the northwest of Mordor, formed at the meeting of the Ered Lithui and the Ephel Dúath, whose northern entrance was guarded by the Morannon.