Native Americans who lived here until about 500 years ago built the ceremonial mound complex at Crystal River. It was settled about 2,500 years ago when the river system and local marine estuary had matured and could provide enough food to sustain a large sedentary population. Throughout the site's occupation, social complexities and ceremonialism changed as populations increased. Although ideas and technologies from other areas filtered in and were adopted, these coastal dwellers retained much of their own cultural identity. Archaeological evidence shows the influence of at least three cultural periods at the Crystal River site.