Isen

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 river, the Adorn. The North-South Road ended on the western shore of the Fords of Isen. There, the Isen passed in two arms around a large eyot. The Fords of Isen were the only place south of Isengard where large armies, escpecially if they were mounted or heavily armed, could cross over the Isen. About a mile east of the gates of Isengard, a bridge had been built over the Isen where it ran through a very deep channel.

In the Third Age, the Isen and the Adorn formed the western 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 during certain periods of the Third Age.

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.

The mouth of Isen was the northernmost landing point of the fleets of the Corsairs from Umbar and Harad that assailed the coasts of Gondor in Third Age 2758 and aided the Dunlendings against Rohan.

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.

Isen represents the Westron name of the river, albeit archaic in form. It is an old variant form of English "iron". The river's name Isen is derived from (the first element of) Isengard, the fortress at its source.

The Sindarin name of the river was Sîr Angren, which means "River of Iron". It is probable that the river's name in Sindarin was also derived from the first element of Angrenost, the Sindarin name of the fortress at its source.

2011: The Lord of the Rings Online:

To the north of the Fords of Isen, both east and west banks of the Isen are explorable. To the south of the Fords, only the north bank is accessible, as the West-march of Rohan is currently not present in the game.

1. Esta ficha se ha importado inicialmente de TolkienGateway.net el día 26/05/2026.