[4] Scholar Anne Christine Taylor notes that, '[o]f all the western Amazonian mission establishments, that of the Jesuits of Mainas was by far the most important'.
[5] She estimates that, prior to the arrival of the Spanish, the many ethnic groups (called Indians or Indios) in the mission field had a population of approximately 200,000.
[6] Throughout their existence, the Jesuit mission settlements, known as reductions, were marked by epidemic disease (often smallpox) that exacted a tremendous death toll on the indigenous people resident in them.
[9] The Jesuits sought to congregate semi-nomadic indigenous people into Spanish-style settlements called reductions, thereby facilitating their Christianization.
The colonial governors sought in addition to subject the indigenous to the encomienda or repartimiento systems of labour extraction, forcing the Indians in the reductions to labor on Spanish farms.
[9] The Jesuit missions offered the indigenous people Christianity, iron tools, and a small degree of protection from the slavers and the colonists.
[20] The Jesuits sought to 'induc[e]' indigenous peoples to settle in reductions, as opposed to their traditional modes of habitation and forms of government.
The Jesuits travelled with soldiers, and the colonial governor would periodically send his forces on entradas—a missionary's initial attempt to establish contact with those he sought to convert, using 'food and gifts' as inducement.
William Lewis Herndon, exploring the Amazon for the United States Navy, described missions in the Mainas region that traded various goods with Brazil.
Indians are punished by flogging or confinement in the stocks; whites are sometimes imprisoned; but if their offence is of a grave nature, they are sent to be tried and judged by the courts of the capital.
[26][27]Herndon also observed that the indigenous inhabitants of the Mainas missions, unique among the 'Indians of Peru', had been exempted from the payment of a head tax, because 'these people had the forest to subdue, and were only able to wring a hard-earned support from the cultivation of the land'.
Over the 129 years of Jesuit missionary activity in the Mainas region, numerous epidemics of smallpox and other diseases exacted a severe toll on indigenous peoples.