West-March

The West-March was a part of Rohan to the West of Helm's Deep. It lay South of the Isen river and North of the Adorn river. Beyond the Isen River was the Gap of Rohan, which led to Isengard.

Behind the Scenes
The West-March is not to be confused with the Westmarch, a land granted to the Hobbits of the Shire reaching to the Tower Hills.