Ephel Duath

The Ephel Dúath, also known as the Mountains of Shadow or the Outer Fence, were a range of mountains making up Mordor’s western and southern borders.
== Description ==
These mountains met the Ash Mountains at the Black Gate, sealing Mordor from the outside. The Morgul Vale, where the city of Minas Morgul stood, was a large valley, opening into the Morgul Pass. The Pass of Cirith Ungol bore secret access through the Ephel Dúath via the dangerous tunnels of Shelob. In the northern reaches of the mountains on the east side lay the castle of Durthang, west of Udûn. The river Poros flowed down out of the mountains to the Anduin, as did the Morgulduin, and another unnamed tributary flowed into the Sea of Núrnen.