The Sacramento Valley of northern California was a rich, diverse environment that supported some of the densest populations of nonagricultural people in the world. Periodic flooding, however, has buried much of the valley's deep cultural history under alluvium. This volume shares the discovery of four buried archaeological sites, including one dating to 7,000 years ago, filled with a diversified assemblage of artifacts and a rich assortment of food remains. Stone net sinkers and associated fish bones represent the oldest fishery ever documented in the interior of California, while items such as marine shell beads and exotic obsidian, and some of the oldest charmstones ever recovered in California provide evidence for long-distance trade networks. The other three sites date between 4000 and 300 years ago and reflect increasing human population density, technological innovation, and the rise of sedentism and territoriality. This historical sequence culminated in findings from a 400- to 300-year-old house complex probably occupied by the Mechoopda Indian Tribe, who collaborated with the authors throughout the project.