The "Early Agropastoralists" period (3,300 BCE - A.D. 400) begins with what appears to have been a shift to a chiefly pastoral lifeway, greater regional interaction, and a more intensive production and circulation of obsidian from the Chivay source area in the Terminal Archaic. In this discussion, the Early Agropastoralists period continues through the Late Formative and subsequently beginning AD400, with the ascendancy of Tiwanaku, the "Late Prehispanic" time block begins. The changes during the Terminal Archaic that mark the beginning of the Early Agropastoralist time include the growing importance of food production, the expanded production and circulation of obsidian, and socio-political differentiation that began to appear in the Terminal Archaic, phenomena of greater interest to this research than the presence or absence of pottery.