About 100 years ago, archaeologists unearthing pottery sherds in Tampa Bay found something unexpected. Some of the fragments they recovered had designs nearly identical to decorated pottery found hundreds of miles to the north. At least on the surface, the pottery appeared to be Mississippian, a culture that emerged more than 1,000 years ago and brought social, economic and political transformation across southeastern North America. For years, archaeologists excluded peninsular Florida from maps of its range, but the artifacts suggested a different story.