Abundant evidence places man in North America about 12,000 years ago. Emigrating from Eurasia, they brought with them one of their most important tools, fire. Their use of fire to manage the landscape was undoubtedly one of the most important influences on southeastern ecosystems. Fire was used to create more abundant resources to supply their needs for survival and eventually their populations flourished. A few years prior to the advent of Europeans in North America, Amerindian populations are estimated to have been about 1.5 to 2 million. Using fire, this large population had cleared most of the cultivatable flood plains in the Southeast where they applied intensive agricultural practices adopted from Mesoamerican cultures. Southeastern Amerindians occupied or utilized almost every acre of land, both uplands and bottoms, as they accomplished their "seasonal rounds", procuring food and other materials. To induce the land to provide its maximum bounty, they burned both uplands and bottoms. For thousands of years these frequent low intensity fires slowly crept over the land creating a mosaic of vegetation that was a fire climax. Savannas and prairies were common and, where present, trees were widely spaced. Evidence supporting this concept is the dominance of disturbance species like pines, oaks, hickories, grasses and herbaceous plants and the presence of bison in the Southeast. Historical eyewitness descriptions further support a fire disturbed landscape.