Background
In the late 19th century, an Amazon rubber boom led to widespread exploitation of indigenous peoples for forced labor, and the accompanying spread of disease and violence caused a roughly 90% decline in the indigenous population of the region. Many survivors withdrew into remote parts of the Amazon, where their descendants continued to live. Conflict between the Cinta Larga indigenous group and rubber tappers, which began in the 1920s, intensified through the 1960s. In 1960, tensions continued as the Cuiabá–Porto Velho (BR-364) highway opened, and the Cinta Larga faced escalating pressure from rubber tappers as well as prospectors seeking gold and diamonds.
The Massacre
The massacre took place at the headwaters of the Aripuanã River in Mato Grosso, at the 11th parallel south, in an area where the Brazilian firm Arruda, Junqueira & Co. was collecting rubber. The attack was planned by the head of the firm, Antonio Mascarenhas Junqueira, who sought to remove the Cinta Larga from the area, reportedly stating that the Indians were "parasites" who should be "eliminated." He hired a plane to drop dynamite on the village and gunmen to attack survivors on foot with machine guns. During the attack, gunmen reportedly killed an infant taken from a breastfeeding mother and killed the mother as well. Thirty villagers were killed; two survived.
Aftermath
The massacre came to light after one of the perpetrators, Atayde Pereira dos Santos, reported it and those responsible to the Serviço de Proteção ao Índio (SPI) Inspectorate in Cuiabá, after he was not paid the amount he had been promised. At the later trial of one of the accused, the presiding judge remarked on the extreme violence, ignominy, egoism, and disregard for human life involved. In 1975, one of the perpetrators, José Duarte de Prado, was sentenced to 10 years' imprisonment but was pardoned later that year; he stated during the trial that it was "good to kill Indians." Although 134 officials were initially charged in connection with alleged involvement in more than 1,000 crimes related to the massacre, none were jailed.
Broader Significance
Details of the massacre were documented in the landmark 1967 Figueiredo Report, compiled by public prosecutor Jader de Figueiredo Correia, which led to the replacement of the SPI with the Fundação Nacional do Índio (FUNAI). The indigenous rights organization Survival International was founded two years after the report's release, partly in response to its findings. The organization has since cited this massacre as an example illustrating why some isolated tribes avoid contact with outsiders.