The surviving mounds of the Toolesboro Mound Group were built by the Havana Hopewell culture sometime between 200 BCE and 100 CE. The status of the people buried in the mounds indicates that the mounds were raised by people working within an organized community with an established social hierarchy. It is believed that there is likely to have been a Hopewell village located nearby, but as of December 2006 the location of this village had not yet been identified. Archeologists conjecture that the Iowa River, shifting its course frequently during the following two millennia and spreading alluvial silt over its path, may have flooded or buried the site.