We have very little information about the occupants of Calenardhon before the arrival of the Rohirrim, but it is known that the fortresses at Aglarond and Angrenost (later known as the Hornburg and Isengard) were established in the western part of this area early in Gondor's history.

Both the size of this region, and the fact that the Gondorians invested in its defence, argue for the existence of other settlements, but none are explicitly recorded. The name Aldburg given to Eorl's first capital (meaning 'old fortress') might hint that it was founded on the site of an earlier Gondorian township, but other interpretations are possible.