From Tolkien Gateway
The Road to Isengard by Alan Lee

The River Isen (or Sîr Angren in Sindarin[1]) was a river that formed the western border of Rohan.


The source of the river was in the southern Misty Mountains, first flowing south through Nan Curunír and across the Gap of Rohan to the edge of the White Mountains, where it abruptly bent west and ran to the sea of Belegaer. At a distance of about 50 lári west of the Gap of Rohan, the Isen was joined by its tributary, the river Adorn.[2] The North-South Road crossed the river at the Fords of Isen where there was a small eyot.[3] About a mile east of the gates of Isengard, a bridge had been built over the Isen where it ran through a deep channel.[4]


In the Third Age Isen and Adorn formed the boundary of the Kingdom of Rohan, but the triangle of land between Isen, Adorn, and the White Mountains was a contested land, claimed by the Rohirrim as well as the Dunlendings.[5]

The Isen formed a natural boundary in the Gap of Rohan, and was only crossable at Isengard or at the Fords of Isen, where the Rohirrim fought a number of great battles against the Dunlendings and Saruman's Orcs in the late Third Age.[6]

The mouth of Isen was the northernmost landing point of the Corsair fleets that assailed the coasts of Gondor in T.A. 2758[7] and aided the Dunlendings against Rohan.[8]

When the Ents attacked Isengard, they dammed the Isen and other springs and streams in Nan Curunír, and dug trenches to divert the river's flow, before breaking the dams and temporarily drowning all of Isengard.[9]


Why the river was called Isen, or "Iron" in modern English, is not known. Presumably the grey pebbles on the bottom and the banks of the river made the water look iron-grey.

See also