The story of Alterac Mountains.
The Alterac Mountains are a cold, rugged range in the north of the Eastern Kingdoms, between Hillsbrad and the Plaguelands, and they hold the ruins of a kingdom that betrayed its own. Alterac was once a proud human nation with its capital in the peaks. During the Second War its king, Aiden Perenolde, sold out the Alliance to the Horde in the hope of saving his throne. The treachery was uncovered, the Alliance marched into the mountains, and Alterac was broken apart.
Its ruins have found new masters. The Crushridge ogres hold what is left of Alterac City, and the Syndicate, a criminal network led by the remnants of Alterac's nobility, the Perenoldes among them, works out of the old towns and the ruined village of Strahnbrad, where the people once took up arms for Prince Arthas at the start of the Third War. The infamous Ravenholdt Manor, hidden deep in the hills, is home to a very different kind of rogue.
To the west, on the shore of Lordamere Lake, lies the crater where Dalaran stood until Archimonde destroyed it in the Third War. The mages of the Kirin Tor have sealed the ruins behind a great violet shield while they rebuild. And deep in the south of the range lies Alterac Valley, where the orcs of the Frostwolf clan have made their home since the First War, and where they and the dwarves of the Stormpike Guard now fight for control.
Written for this site from the game's lore. Further reading: Alterac Mountains on Warcraft Wiki.

