Middle-earth is the fictional land where Mordor is located in J.R.R. Tolkien’s legendarium.
Mordor lies in the southeastern part of Middle-earth and serves as Sauron’s principal realm during The Lord of the Rings. It is surrounded by mountain ranges and contains Mount Doom, the volcanic site where the One Ring was forged and where it can be destroyed.
The term Middle-earth does not mean the entire planet in Tolkien’s setting. It refers to the central regions of Arda, the world created in his mythology, especially the lands where many of the major stories take place. The setting includes the Shire, Gondor, Rohan, Moria, and Mordor.
Valinor is a blessed land across the sea, Númenor is a lost island kingdom, and Beleriand is a First Age region. These places belong to Tolkien’s wider world but are not the name of the land containing Mordor.