When Thorin Oakenshield died during the Battle of Five Armies, his close kinsman Dáin Ironfoot from the Iron Hills stepped in to lead the people of Durin. Under his reign, Erebor has thrived, enjoying good relations with the neighbouring realms, and the magnificence of the Kingdom under the Mountain itself has exceeded Thorin’s dreams: the vast underground stronghold, dug after the fashion of the Dwarves since they first awakened in Middle-Earth, is now the most prosperous dwarf-colony active in the Northern world.
Dwarf craftsmen labour in the city of Dale, Barding apprentices work the bellows in the forges under the mountain, and traders come and go from the Front Gate of Erebor to bring the products of the Dwarves’ cunning handiwork to distant lands. Innumerable treasures of worth far surpassing anything made by modern hands are said to grace the deep chambers of the Dwarven city. The few envoys who have been granted access to the halls of the King speak of the wonders of the subterranean palace, foremost among them that which now sits on the unmoving breast of Thorin Oakenshield: the fabled Arkenstone, Heart of the Mountain.