Mountain Kingdom

An occasional name for Erebor, the Lonely Mountain to the northeast of Mirkwood. It first became the seat of the Kings of the Longbeard Dwarves after the fall of Khazad-dûm, when Thrán I led many of the survivors of Durin's Bane out of the Misty Mountains. They found their way to the Lonely Mountain, a single tall northern peak, and beneath it they founded a new kingdom, commonly called the Kingdom under the Mountain.

That first settlement of the Mountain Kingdom did not last for long. Many of the other Longbeards had gathered in the Grey Mountains to the west, and Thráin's successor Thorin I left Erebor to join them there. After that time the Mountain Kingdom had no King for nearly four hundred years, until Thráin's descendant Thrór led his people back to the Lonely Mountain and refounded the Dwarf-kingdom there. The riches of the new King under the Mountain became famous far and wide, and they reached the ears of the Dragon Smaug, who descended on Erebor and sacked it in III 2770.

Thrór's grandson was Thorin Oakenshield, who dwelt with his people in exile in the Blue Mountains, far to the west of the Mountain Kingdom. Thorin set out to avenge his people by destroying Smaug, and led a quest back into the east with the help of the Wizard Gandalf, the Hobbit Bilbo Baggins, and a company of his own followers. Through a series of remarkable and unpredictable events, they succeeded in recovering the Lonely Mountain from Smaug, but Thorin was lost in the Battle of Five Armies shortly afterward. He was succeeded by his cousin Dáin Ironfoot, and under Dáin and his successors the Mountain Kingdom remained the seat of the Kings of Durin's Folk on into the Fourth Age.