Dúrin's Folk, also called the Longbeards, are the oldest and most important folk of all the Dwarves in Middle-earth. They are one of the seven kindreds of Dwarves whose leaders were from the House of Dúrin. Their first king was named Dúrin the Deathless, who was one of the seven Fathers of the Dwarves.
In the deeps of time the Fathers of the Dwarves awoke. Dúrin, who had slept alone at Mount Gundabad, wandered south along the Misty Mountains until he came upon Azanulbizar and in the caves above Kheled-zâram he founded the city of Khazad-dûm, the home of Dúrin's Folk. Dúrin lived there so long he became known as Dúrin the Deathless, yet in the end he died before the end of the First Age.
When Humans first migrated west into Rhovanion and Eriador, they encountered Dúrin's Folk. The Longbeards were the wisest and most farseeing of the seven kindreds and began dealing with Humans, establishing an economy in which Humans chiefly provided food in exchange for Dwarven work in building, road-construction, mining, and the crafting of tools and weapons. During this period the Longbeards adopted the speech of Humans, keeping their own language to themselves.