Malenhad was a region that divided up a small portion of what was known as the The Witch-Realm of Angmar. The region was described as a marshland, south of the Nan Angmar.
Malenhad wasn't necessarily called "Malenhad" by its inhabitants. It was called by its two names of West Malenhad and East Malenhad which had small differences. The Western portion of this region was much more dry than the eastern. Although, they shared the same purpose of housing and preparing the forces of the Witch-King.