Who were the moundbuilders?

The Mound Builders were a group of ancient Native American cultures known for constructing large earthen mounds for various purposes, including burial sites, ceremonial centers, and platforms for structures. They primarily inhabited the Ohio River Valley and surrounding regions, with the most notable cultures being the Adena, Hopewell, and Mississippian. These societies thrived from approximately 1000 BCE to 1600 CE, showcasing complex social structures and trade networks. Their impressive mounds, such as Cahokia in Illinois, reflect their architectural and cultural achievements.