Prosecutors in Brazil have opened an investigation after reports that illegal gold-miners on a remote Amazon river massacred at least 10 members of an "uncontacted" indigenous band. If confirmed, this means up to a fifth of the entire band have been wiped out. Two gold-miners have been arrested in the case. The killings allegedly took place last month along the Rio Jandiatuba in the Vale do Javari Indigenous Territory, a huge area  in Amazonas state bordering Peru. The region is known as the "Uncontacted Frontier," as it shelters more isolated peoples than anywhere else on Earth. Reports of the massacre only emerged after the miners started boasting about the killings, showing off "trophies" in the nearest town.

The trophies included a bow, an arrow and a carved paddle taken from a canoe as proof of the encounter. At the end of August, army troops and personnel from the environment agency IBAMA raided mining camps in the area, destroying four dredges and making the arrests. Brazil's indigenous affairs agency FUNAI has confirmed the attack is under investigation. Women and children are believed to be among the dead.

In a second case, villagers in Jarinal, a Kanamari community on the Rio Jutai reported an attack against a group of the related Wakinara Djapar people, possibly carried out by settlers who are farming illegally in the Vale do Javari territory. That report is also under investigation, but no arrests have been made.

Flying over the area in December 2016, FUNAI staff saw the charred remains of an isolated group's maloca or communal house, although it is unknown whether the burning was related to incursions by outsiders. (Mongabay, Sept. 11; Survival International, Sept. 8)

Last month also saw indigenous organizations and civil society groups holding mobilizations in Brazil, centered around Aug. 9, International Day of the World's Indigenous People. Demonstrators accused the government of moving to reduce indigenous land rights, and demanded Brasilia open a dialogue with indigenous representatives. Of greatest concern is President Michel Temer's recommendation to approve the "marco temporal"—a 1988 cut-off date for indigenous occupation of traditional lands. Critics say the marco temporal is designed to deny indigenous land rights guaranteed under Brazil's 1988 constitution, while legalizing the claims of land thieves. (Mongabay, Aug. 14)