The earthwork had been built, however, by the early Hopewell culture (200 BC-500 AD) at least 1,000 years prior to the arrival of the Fort Ancient culture.
Dessa jordarbeten hade dock byggts av den tidiga Hopewellkulturen (200 f.Kr till 500 e.Kr) åtminstone 1 000 år före Fort Ancient-kulturens ankomst.