Rohan, is a fictional realm in J. R. R. Tolkien's fantasy era of Middle-earth. It is also referred to as Riddermark or The Mark. (The Mark is believed to have been the Mercian name for the Anglian Kingdom of Mercia.) The realm is of significant importance in the author's most famous book, The Lord of the Rings.
Rohan is a grassland which lies north of its ally Gondor and north-west of Mordor, the realm of Sauron, their enemy (see maps of Middle-earth). It is inhabited by the Rohirrim, a people of herdsmen and farmers who are well-known for their horses and cavalry.
Conceptualized as the "Horse Kings of Rohan" allied with Gondor in early drafts of 1939, the Rohirrim took their final form in 1942 when about one third of The Lord of the Rings was completed.