Dwarves of the Blue Mountains
After the War of Wrath, much of the Ered Luin fell into the sea, taking the Dwarf city of Nogrod home of the Firebeards Dwarves with it (which later became the Gulf of Lhún), and ruining Belegost to the south, the home of Broadbeams. Many of the Firebeards and Broadbeams left the Ered Luin for Khazad-dum becoming part of Durin's folk, while some stayed to help rebuild what they could of what later became the northern halls of the Dwarves, and the remnants of Belegost in the southern chain.
For thousands of years the Dwarves toiled in the Blue Mountains. Working the lesser mines and rebulding what was left of their ancient kingdom. They most likely traded with Elves of Mithlond during the Second through early Fourth Ages, and with the Men of Arnor in the late Second Age through the Third Age.
In the year 1981 the Balrog was awoken in Khazad-dum, and the Dwarves fled for the Grey Mountains and the Lonely Mountain, and possibly some Dwarves fled to the Blue Mountains. Durin's folk of the Grey Mountains were driven fled from their halls by Cold-drakes in 2589. In 2770 Smaug the Dragon attacked the Lonely Mountain and drove the Dwarves off. They went into exile and wandered to Dunland to eke out a living. But king Thrór was murdered by Azog the Goblin chieftain when Thrór went to see Khazad-dum (now called "Moria" "the black pit"). This tragedy would start the War of the Dwarves and Orcs, in which Thrór's son Thráin II called all the houses of the Dwarves together to seek revenge on the Orcs. This was the first conflict since the Battle of Unnumbered Tears, thousands of years before that the Dwarves of the Blue Mountains had fought in. The armies of the Dwarves sacked every Orc-hold in the Misty Mountains, and in 2799 the final battle came at the slopes of the East-gate of Moria in the Battle of Azanulbizar. The Dwarves won in the end, but half the of those who particapated were killed. So Durin's folk moved to the Blue Mountains, where they started a new kingdom. Years later, king Thráin II was going to reclaim the Lonely Mountain from Smaug, but was ambushed by Orcs on the eaves of Mirkwood. He was tortured for four years in the dungeons of Dol Guldur until his death. Thorin II Oakenshield, became king of Durin's folk in the Ered Luin, until he left on the Quest of Erebor to reclaim the Lonely Mountain. He succeeded in his quest but was killed in the Battle of Five Armies He was succeeded by his cousin Dáin II Ironfoot from the Iron Hills. It is not known who became the leader of the Dwarves in the Ered Luin.
The Dwarves of the Blue Mountains, lived in their halls through the Fourth Age, but not much is known about what happened to them.