The viability, and even the existence, of intensive agriculture in the prehispanic Amazon Basin has long been debated. The presence of large areas of raised fields demonstrates that intensive agriculture was practiced in the Llanos de Moxos in eastern Bolivia before the arrival of Europeans in the late 17th century. However, early historic sources do not specifically refer to this type of agriculture, which raises the questions of how and why farmers abandoned their fields. Recent fieldwork in Moxos addresses these questions.  Radiocarbon dating of occupation sites associated with raised fields provides a baseline for studying the dynamic process of abandonment. Several causal factors for agricultural abandonment are touched upon in this article, including the impact of European exploration and colonization, epidemic disease and massive climate change.  These hypotheses are evaluated in terms of changes in settlement and field use in late prehispanic and early historic Moxos.

Keywords: Amazon, agriculture, raised fields, archaeology, Conquest, Bolivia