From the late sixteenth century, expeditions from the frontier town of São Paulo ranged over the Brazilian interior in search of indigenous captives to work the sugar and wheat farms of the south, and later in search of gold. Between 1628 and 1632 large bandeiras under Antônio Raposo Tavares and others attacked the Spanish Jesuit reductions of Guairá, west of the Paraná, destroying the mission towns and driving their Guaraní inhabitants back to São Paulo in coffles; the Jesuits evacuated what remained of the population downriver in 1631 and resettled it further south. Raiding continued against the missions of Itatín and Tape until the Guaraní, permitted firearms by the Spanish crown, defeated a bandeira at Mbororé in 1641. Portuguese law repeatedly restricted and then permitted indigenous enslavement — the crown prohibited it in principle in 1570, 1609 and 1680 while allowing capture in 'just war' and the ransom of captives from other Indians — and the traffic continued under those exceptions. Brazilian nationalist historiography long celebrated the bandeirantes as pioneers of the nation's territory; that commemoration is now contested in Brazil precisely because of the slaving.
Slave-raiding expeditions from São Paulo, the bandeiras, seized indigenous people across the Brazilian interior, destroying the Jesuit Guaraní missions of Guairá and extending Portuguese claims deep into Spanish territory
The raids ran from Sao Paulo across Guaira, the Parana-Paraguay basin, Minas Gerais and the Amazon fringe between 1580 and 1720, acting on dozens of unenumerated indigenous societies. The only counted population is that of the Jesuit reductions: the Guaira missions held on the order of tens of thousands of Guarani when they were destroyed in 1628-32, and the Parana-Uruguay reductions to which the survivors fled numbered around 40,000 in the 1640s. Estimates of Brazil's indigenous population in 1500 range from about 2.4 million (IBGE, following Rosenblat) to 5 million or more, but none of these can be attached to the specific interior the bandeirantes raided.
No defensible total. Jesuit accounts describe heavy mortality during the raids and on the forced marches to São Paulo, and epidemics repeatedly swept both the mission towns and the captive populations; the sources are partisan and record neither captives nor deaths systematically.
The burning of mission towns, the killing of those who resisted, the marching of captives in chains to São Paulo and the seizure of children are described in Jesuit reports and Spanish colonial complaints, and summarised in the reference literature on the bandeiras.
Brazil, Paraguay, Argentina