BETWEEN AD 530 and the early 1500s, the people of the Andes built complex systems of irrigation, aqueducts and raised fields in the tropical mountains of present-day Bolivia, Ecuador and Peru. Their accomplishments supplied crops and the economic and symbolic bases of power for some of the world’s most notable early civilizations, including the Empires of the Tiwanaku (similar to AD 100-1000) and Inka (similar to AD 1400-1532), as well as smaller chiefdoms(1-6), But there has been no direct evidence of extensive irrigation, the most common water control, before about AD 1000. Here we demonstrate, by studies of sedimentology and geomorphology near Tarata village in the Bolivian Andes, that an extensive and integrated system of floodwater and canal irrigation was in use at about AD 719 and that it functioned as early as 3,500 years before present (BP). A modern-day equivalent continued in use until 1993. The findings at Tarata give a detailed example of early irrigation that would have enabled the development of water control by Andean civilizations in highland settlements above 2,000 m.