On who they are, I believe that their names are good descriptions: the Blacklocks probably had black beards and hair, and the Ironfists were probably strong and agressive. As for where they went, I believe that they originally had contact with eastern houses of Dwarves, making pilgrimages to Mount Gundabad. After the mountain was taken by the Goblins, and contact all but ceased (keep in mind this is just my opinion) they may have developed their own civilization without any contact with other Dwarves, but with contact with local Avari and Easterlings.