This is the legacy report of an extensive joint US/Afghan archaeological project in the southwest quadrant of Afghanistan: the Smithsonian Institution/ Afghanistan Institute of Archaeology Helmand-Sistan Archaeological Project, 1971-1976. While the fieldwork was conducted in the 1970s, political events in Afghanistan over the past half century make this the first major archaeological synthesis of the region and the only one for decades to come. The Helmand River is one of the main routes between the Middle East, South, and Central Asia over the past 5,000 years and project findings reflect that cross-cultural mixing of cultures. The research identified key monuments from Bronze Age, Persian, Greek, Buddhist, Zoroastrian, and Islamic cultures, and explored the role of intensive irrigation agriculture in one of the world's driest regions. Volume 1 describes the 200 archaeological sites surveyed or excavated by the survey and their material culture.