An indigenous man who has been living alone and isolated in the Brazilian Amazon region for more than 25 years has died.

This emerged from a statement by the movement for indigenous peoples "Survival International" on Monday (local time).

According to the Brazilian Indigenous Authority Funai, which observed him, the man was found dead in a hammock during a round of checks without signs of violence.

"Everything points to a natural cause of death," said Funai, the authority responsible for indigenous peoples.

According to media reports, the body was covered in parrot feathers - which one expert says could indicate the tribal knew he was going to die.

Known as "Índio Tanaru" or "Índio of the Hole," the indigenous man who dug deep holes to trap animals and hide was thought to be the last survivor of his people and the sole inhabitant of the Tanaru indigenous territory in Rondônia state on the border to Bolivia.

Human rights activists believe the remaining members were killed by ranchers when they entered the area in the 1970s and 1980s.

Brazil's "wild west"

The region is known as Brazil's Wild West, where land conflicts are often fought out with weapons.

"It symbolized both the appalling violence and cruelty inflicted on tribal peoples in the name of colonization and economic gain, and their resistance," said Survival International's Fiona Watson, according to the statement.

"With his death, the genocide of this indigenous people is complete," Watson said. "It was truly a genocide: the deliberate annihilation of an entire people by cattle ranchers hungry for land and wealth."

Around 800,000 indigenous people live in Brazil out of a total population of more than 212 million people.

In the Amazon rainforest there are still a number of small indigenous groups who have no contact with the outside world.

According to the Funai authority, such groups have been registered in 114 locations across the country;

but the numbers vary.