Numerous pre-Columbian sites with artificial earth mounds have been found in the Upano valley, at the foot of the Andes, in the Ecuadorian Amazon. Large-scale excavations conducted during a Franco-Ecuadorian project helped to reveal techniques in building, mound functions, chronology of occupation, and house plan and associated activities. Groups of the Upano culture built these mound complexes from 500 BC and left the valley ca. 400–600 AD. These groups transformed the natural landscape, building hundreds of earth mound complexes along terraces. Located at a key-area, the Upano people had strong relationships with the Andean highlands, where they traded their pottery. The most striking aspect is the existence of a spatial pattern organizing the mounds. The delimitation of a square or rectangular, low, and flat plaza is the basis of the spatial pattern in the Upano valley. It is closed on four sides by mounds, modified slopes, banks or dug pathways. Variations occur, but the basic pattern is generally the same. In several complexes, a central mound is built in the center of the plaza with four or six peripheral elevations. (source éditeur)