The Blue Mountains are the home to many dwarves after having to flee their home in Erebor due to an attack for Smaug – a dragon.
Thorin II Oakenshield, the king of the Blue Mountains left – after living there for 380 years – with 12 trusted companions to reclaim Erebor as their own. Dwalin, Balin, Fíli, Kíli, Dori, Nori, Ori, Oin, Gloin, Bifur, Bofur, and Bombur.
After finally taking back The Lonely Mountain, most of the dwarves returned to their old home. Some stayed behind in the Blue Mountains.