The history of the Southern United States spans back thousands of years to the first evidence of human occupation. The Paleo-Indians were the first peoples to inhabit the Americas and what would become the Southern United States. By the time Europeans arrived in the 15th century, the region was inhabited by the Mississippian people, well known for their mound building cultures. European history in the region would begin with the earliest days of the exploration and colonization of North America. The countries of Spain, France, and England eventually explored and claimed parts of what is now the Southern United States, and the cultural influences of each can still be seen in the region today. In the centuries since, the history of the Southern United States has recorded a large number of important events, including the American Revolution, the War of 1812, the American Civil War, the expansion and then ending of slavery in the U.S., the First Great Migration, the Second Great Migration, the Jim Crow era, the American Civil Rights Movement, the 1996 Summer Olympics in Atlanta, and the economic and population transformation of the South during the mid-to-late 20th century. Following World War II, industrialization and economic growth further gained speed across the South. Since the late 20th century, the South has seen the arrival of many migrants from other U.S. regions, as well as different international immigrant groups. Native American civilizations In Pre-Columbian times, the only inhabitants of what is now the Southern United States were Native Americans. At the time of European contact, much of the area was home to several regional variants of the Mississippian culture, an agrarian culture that flourished in the Midwestern, Eastern, and Southeastern United States. The Mississippian way of life began to develop around the 10th century in the Mississippi River Valley (for which it is named). Notable Native American nations that developed in the South after the Mississippians include what are known as "the Five Civilized Tribes": the Cherokee, Chickasaw, Choctaw, Creek, and Seminole. European colonization Spanish exploration Spain made frequent exploratory trips to the New World after its discovery in 1492. Rumors of natives being decorated with gold and stories of a Fountain of Youth helped hold the interest of many Spanish explorers, and colonization eventually followed. Juan Ponce de León was the first European to come to the South when he landed in Florida in 1513. Hernando de