Mississippian people constructed enormous earthen pyramids throughout the USA Midwest and South, they even played an early version of lacrosse.
The Mississippian culture was a mound-building Native American culture that flourished in what is now the Midwestern, Eastern, and Southeastern United States from approximately 800 CE to 1500 CE, varying regionally.
The Mississippian way of life began to develop in the Mississippi River Valley (for which it is named). Cultures in the tributary Tennessee River Valley may have also begun to develop Mississippian characteristics at this point. Almost all dated Mississippian sites predate 1539-1540 (when Hernando de Soto explored the area).
The Mississippian stage is usually divided into three or more periods. Each of these periods is an arbitrary historical distinction that varies from region to region. At one site, each period may be considered to begin earlier or later, depending on the speed of adoption or development of given Mississippian traits.
Early Mississippian cultures had just transitioned from the Late Woodland period way of life (500–1000 C.E.). Different groups abandoned tribal life ways for increasing complexity, sedentism, centralization, and agriculture. The Early Mississippian period was from c. 1000 to 1200 C.E. Production of surplus corn and attractions of the regional chiefdoms led to rapid population concentrations in major centers.
The Middle Mississippian period is often considered the high point of the Mississippian era. The expansion of the great metropolis and ceremonial complex at Cahokia (in present-day Illinois), the formation of other complex chiefdoms, and the spread and development of SECC art and symbolism are characteristic changes of this period. The Mississippian traits listed above came to be widespread throughout the region. In most places, this period is recognized as occurring c. 1200–1400 C.E.
The Late Mississippian period, usually considered from c. 1400 to European contact, is characterized by increasing warfare, political turmoil, and population movement. The population of Cahokia dispersed early in this period (1350–1400), perhaps migrating to other rising political centers. More defensive structures are often seen at sites, and sometimes a decline in mound-building and ceremonialism. Although some areas continued an essentially Middle Mississippian culture until the first significant contact with Europeans, the population of most areas had dispersed or were experiencing severe social stress by 1500. Along with the contemporary Anasazi, these cultural collapses coincide with the global climate change of the Little Ice Age. Scholars have theorized that drought and the collapse of maize agriculture, together with possible deforestation and over hunting by the concentrated populations, forced them to move away from major sites.