Eriador is the region in Middle-Earth where both the LotR trilogy and LotRO start. It stretches from Ered Luin (the Blue Mountains) in the east, to the Misty Mountains in the west. People of all races live here. Hobbits dwell in The Shire, Dwarves in Thorin's Hall, and elves scattered throughout Eriador but mainly in Ered Luin and Rivendell. Men can be found everywhere in Eriador, but primarily in Breeland, Lone-Lands, and the North Downs.

In the northeast lies Angmar, evil's main stronghold in Eriador. The last remains of Arnor became The Witch-King's first castle. He lost the war against an army of free elves and men only to return. He has now built a massive army of goblins, half-breed, troll and orcs which roams through Eriador. His army is marching south, and a huge battle has begun in the Ettenmoors.