In the Lower Platte River valley, villages affiliated with the Central Plains Tradition were part of a vast prehistoric Native American population that lived in Nebraska from A.D. 1000 to 1400. These people built and lived in permanent earth lodges, grew crops, and hunted a variety of wild animals, and their artifacts included many finely crafted tools, pottery vessels, and ornaments. The lodges now survive only as ruins marked by subtle changes in soil color and texture, with occasional charred posts, rafter sections, and other evidence. Their inhabitants dug basement-like foundations one to three feet deep, built substantial timber frameworks above them, and excavated large storage chambers in the house floors for corn and other food; when rodents or water seepage damaged these chambers, they were filled with trash. This successful adaptation apparently failed as climatic deterioration and resource depletion led Central Plains people to expand northward, and between A.D. 1300 and 1400, sites similar to those once in Nebraska appeared in South Dakota. Conflict followed between Central Plains Tradition people and tribes already living along the Upper Missouri, and by 1400 there is no archaeological evidence for Central Plains people. New groups moved into the region during the 1600s and 1700s, ancestral to the Pawnee, Omaha, Ponca, and Oto.