The Gap of Rohan was the broad open land between the southern end of the Misty Mountains and the northern spur of the White Mountains, the chief gateway between Eriador and the South and the easiest road into Rohan from the west. Isengard stood guard at its northern mouth; and because Saruman held that fortress, the Gap was closed to the Fellowship, who were forced instead to attempt the pass of Caradhras and then the dark road through Moria.