In the 1800s, the "Moundbuilders Myth" claimed that a lost civilization had built the mounds. Some thought the builders were giants. In the 1890s, the Smithsonian Institution proved through extensive excavations that ancestors of historic Indians built the mounds.

Adena people built mounds over the bodies of important people, such as chiefs and shamans. The mounds were built in stages, with some containing structures such as log tombs. Many Adena burial mounds contained exotic goods such as copper from the Great Lakes, shell beads from the Gulf Coast, and mica from the southern Appalachians.

Large earthworks, similar to Hopewell were not common. As time went on, Indians continued living in scattered hamlets and mound building was not as prominent, although Fairchance Mound in Marshall County had a large burial mound associated with its settlement.