This book focuses on archaeological sites and artifacts related to the Formative societies known as Qaluyu and Pukara (1400 BC-350 AD). These societies developed in the northern basin of Titicaca, in the Department of Puno, Peru. Focussing on the site of Chaupisawakasi, Chapter 1 describes the natural environment of the northern Titicaca Basin, and in particular the valley of Quilcamayo-Tintiri, a tributary of Azángaro River. Chapter 2 assesses the authors' work in regard to previous research in the region with a focus on the survey results from 2007 and 2008. Chapter 3 provides detailed descriptions of archaeological excavations carried out in 2010 at the site of Chaupisawakasi. Chapter 4 describes the analysis performed on materials from the excavations at the site of Chaupisawakasi. Specific data analyzed include pottery, lithic, botanical and zoological. Finally, Chapter 5 presents the authors' interpretations of Chaupisawakasi. They explain the history of the site and its passage from a communitarian society in Qaluyu to a different society that was imposed by the Pukara state, using comparative data from sites from the same period in the Quilcamayo-Tintiri valley and other areas of the northern Titicaca Basin. Finally, this volume offers some suggestions for future research in the Quilcamayo-Tintiri valley in particular in the northern basin of Titicaca in general.