The character and development of complex societies has been one of the major interests of Amazonian archaeology. This article presents an ontological interpretation to explain the socio-political organization and importance of ritual in the Santarém area, Lower Amazon, Brazil, during the late pre-colonial period (ad 1000–1600), drawing from the contributions of Viveiros de Castro on Amazonian ontologies and Pierre Clastres on the constitution of power in the South American tropical lowlands. This approach affords new insights into the spatial organization of large habitation sites, the settlement patterns of nearby smaller sites and the pragmatic role of ritual objects. The data point to demographic growth, elaborate spatial organization and the existence of independent villages, probably resulting from fissions. The distribution of objects used in ritual contexts suggests a network employing a mytho-cosmological iconography that emphasizes bodily metamorphosis, indicating a predatory ontology related to Amerindian perspectivism and the presence of institutionalized shamanism. The text argues for the existence of distinct cosmopolitical strategies used to maintain the egalitarian order and that the flows of knowledge, sacred artefacts and religious specialists within the wider social sphere structured regional relations.