The Northlands is a name used to refer to different lands in the continent of Lordaeron.
The first use of the term was during the Second War, to refer to much of the continent of Lordaeron, including the areas around Tyr's Hand, Tyr's Bay, Darrowmere, Caer Darrow, Stromgarde, Lordaeron, and Alterac.
The term was later used to refer to the northern lands inside the kingdom of Lordaeron itself, where cities such as Stratholme, Andorhal, Hearthglen and Tyr's Hand are located. This was the area where Kel'Thuzad owned some warehouses. In these warehouses, he conducted experiments on rats in order to create an undead rat army in case of another war. His experiments were a failure, and the Kirin Tor confiscated all his property calling these experiments nefarious. This area was the first hit by the Plague, and later became the Western and Eastern Plaguelands.