Much research has been done on this topic, and there is different names for different eras. Obviously the answer varies by location, so I’ll focus on the Mississippians of the St. Louis area. All were hunter-gatherers until they eventually established settlements. The Mississippians began their settlements during the Medieval Warm Period, a time in history when the Mississippi River’s flood levels were rather low, allowing for massive farms that could support large urban areas. Massive mounds were being built, and trade routed reached as far north as the Great Lakes, east as the Smokies, south as the Gulf of Mexico, and west as the Rockies. The society flourished, but a number of factors, including political instability, a large fire, and the floods all contributed to the ultimate downfall of Cahokia. The floods destroyed farmland, food supplies, and homes. Eventually the area was abandoned and used only for ceremonial purposes. Floridians tribes who lived on and around shell middens did not experience the same level of destruction until European contact. Without a specific region, I can’t really give you specific lifestyles.