The Seven Fathers of the Dwarves were the first of their race. It is told in The Silmarillion that the Vala Aulë created the Dwarves because he was impatient for the arising of the Children of Ilúvatar (Elves and Men). He created seven Dwarves, and was teaching them the language he had devised for them (Khuzdul) when Ilúvatar confronted him. Aulë offered his creations to Ilúvatar, who accepted them and gave them life.
However, the Fathers of the Dwarves had to wait until the Elves first arrived, and Aulë laid them to rest in various places in the continent of Middle-earth.
The eldest of all, Durin, "lay alone" at Mount Gundabad in the north of the Misty Mountains. He later founded the line of the Longbeards (or Sigin-tarâg in Khuzdul), the Dwarves which were most friendly to the Elves and Men, mostly referred to as Durin's Folk. His city was Khazad-dûm.
The other four Fathers of Dwarves were laid to rest in the far east, two of them at the northern end of the Orocarni, and the other two near the southern end of the range. These founded the lines of the Ironfists and Stiffbeards, and Blacklocks and Stonefoots. No Dwarves of these lines appear in the tales: however, as noted below, the Longbeards may be formed out of Dwarves from all lines, and Dwarves from Durin's Folk may therefore have ancestors from these other lines. After the end of the First Age, when the ancestral homes of the Broadbeams and Firebeards were destroyed, these two lines merged with Durin's Folk, so that Moria had a mixed population, and Thorin Oakenshield grew up in the remnants of the Firebeards' halls.
Of the Fathers of the Dwarves, only Durin is said to have "lain alone". This can be interpreted as referring to the fact he was indeed laid down to rest alone while the other Fathers were laid to rest in pairs, but older versions of the story suggest that it meant Durin alone had no female companion. The other Fathers did: references are made by Tolkien to the "Thirteen Dwarves" created by Aulë (Durin and the six pairs). By this version of the story, Durin's Folk was formed out of Dwarves from the other six lines, as a mixed people arose when all Dwarves went to Gundabad.