The dating of origins of the standing stones at Dúnharg is far from clear, except that we can be sure that they were used by the Men of the Mountains during the Second Age. It is perhaps notable that similar structures were made by Men on the distant Barrow-downs that were said to date back even to the First Age. We have no evidence of a direct connection, but the similarity at least implies the possibility that the earthworks of Dúnharg also dated back to that ancient time.

The use of the word harg by the Rohirrim (for 'temple' in their language) was based on the supposition that the rows of standing stones at the site represented a temple of some kind for the Men of the Mountains. In fact, the original purpose of the place had been forgotten by the time the Rohirrim gave it a name in their own tongue. That name, Dúnharg, is usually modernised to Dunharrow, using the element '-harrow' for an ancient temple seen in various real British place-names.