Coldfells

Coldfells was a hilly region in which Aragorn's grandfather Arador was captured and slain by hill-trolls. Their geography is uncertain (all that is known for sure is that they lay to the north of Rivendell) but circumstantial evidence suggests that they were probably synonymous with the region known as the Ettenmoors. This is based on a description of the Ettenmoors in The Fellowship of the Ring I 12, where they're described as "the troll-fells north of Rivendell." It seems rather unlikely that there were two separate sets of troll-infested moorland in this area.