Oneota is a designation archaeologists use to refer to a cultural complex that existed in the Eastern Plains and Great Lakes area of what is now occupied by the United States from around AD 900 to around 1650 or 1700. Based on the classification defined in Gordon Willey and Philip Phillips' 1958 book Method and Theory in American Archaeology, the Oneota culture belongs to formative stage. The culture is believed to have transitioned into various Siouan cultures of the protohistoric and historic times, such as the Ioway.
Oneota is considered a major component of Upper Mississippian culture. It is characterized by globular, shell-tempered pottery that is often coarse in fibre. Pieces often had a spherical body, short necks and/or a flat lip. Sometimes the vessels had strap handles. Decoration includes wavy and zigzag lines, often in parallel. Most decoration was done on the top half of the vessel. One site occupied by the Oneota people for a period was the Aztalan site beside the Crawfish river in Wisconsin.