In J.R.R. Tolkien’s Middle-earth, the gap between the Misty Mountains and the White Mountains is called the Gap of Rohan.
The Gap of Rohan lies at the western edge of Rohan, where the two great mountain ranges draw close together. It forms an important natural passage between the lands north and south of the mountains. The River Isen runs through the wider region, and Isengard stands nearby at the southern end of the Misty Mountains.
The location is strategically important in The Lord of the Rings. Saruman’s fortress of Isengard controls the approach from the west, while Rohan’s defenses include Helm’s Deep farther east in the Westfold. The gap therefore connects geography with the military movements of the War of the Ring.
A common mix-up is the Gap of Isen, which refers to the passage and surrounding area associated with the River Isen. That name is related to the same western frontier but is not Tolkien’s standard name for the gap between the two mountain ranges.