The Guaraní and the Jesuits built a self-governing, armed republic of about thirty mission towns whose army wiped out a Portuguese slaving expedition in 1641. In 1750 two European kings traded the land away in the Treaty of Madrid, and the Guaraní went to war rather than obey. The episode centers Guaraní agency and ends on UNESCO ruins and a living language.
Historians argue whether the reductions were a humane Indigenous commonwealth or a benevolent but total Jesuit-run order; they were more autonomous than other missions yet still directed. Entry was constrained by slavers on one side and forced labor on the other. The Caiboaté casualty ratio is the victors' count.