Between the Misty Mountains and the White Mountains lay a long, narrow valley known as Rohan Gap.
It connected Arrodes and the Kingdom of Rohan.
And in between the Gap flowed the River Isen from the north, which was turbulent but became calm at the Gap, suitable for crossing the river.
Hence, the location was also known as the Crossing of River Isen.
Since the other side belonged to the territory of the white-robed wizard Saruman, Rohan did not pay much attention to the defense here.
There was only the echoing Hornburg, mainly to guard against the Dunlendings who might return to the fray.
However, unbeknownst to them, the Dunlendings had long since pledged their allegiance to Saruman, plus the strong Orc army secretly crafted by Saruman was ready and waiting nearby, with far greater forces than Rohan.
Just as the Fellowship of the Ring was heading south from Loslorien in the north toward this direction.
