Shell cups carved with mythical beings. Large effigy pipes. Beaded baskets. These are among the archaeologically significant objects excavated from the Spiro Mounds. Often overlooked, this Native American site in the midwestern U.S. is among the greatest sources of Mississippian Native American artifacts ever discovered. Located on the Oklahoma and Arkansas border, the Spiro Mounds were part of a city complex populated from 800 to 1450 A.D. At its peak, it supported a population of some 10,000 people. The Mississippian political, trade, and religious confederation incorporated more than 60 different tribes and stretched from the Gulf Coast of Florida to the Great Lakes and from the Rockies to the Virginia coast.