The Isen River System
The River Isen (Iron River) begins at the southern end of the misty mountains near the ruins of Isengard, and flows three hundred miles westward into the Great Sea in the southern regions of the Enedwaith. The Isen's major tributaries include the river Adorn. The elves once, in the mists of time called the Isen the River Angren, which also means the Iron River. he ruins of Isengard, only the tower of Orthanc still stands, pays testimony to the power of the Ents. The fords of Isen are the crossing-point on the upper reaches of the River Isen. As the only direct route between Eriador and Gondor, the Fords had great strategic value, and Isengard was built to guard them. They were the scene of two Battles between Saruman and the Rohirrim during the War of the Ring.
The River Adorn begins in the western heights of the White Mountains and flows roughly northwestwards to meet the Isen on the borders of Enedwaith. The Adorn defines the western border of the country of Rohan.