An official from Brazil's Indian affairs department, FUNAI, said that "There is a real risk of genocide if FUNAI is not able to protect the Piripkura's land."
The last two known members of the Piripkura tribe live in the Amazon forest in the state of Mato Grosso. Their territory is in the Colniza district, which is estimated to be the most violent area in Brazil, and one of the worst in the Brazilian Amazon for deforestation.
The international organization Survival, which fights for the human rights of tribal peoples, is launching an urgent campaign asking the Brazilian government to sign the Piripkura's land into law and protect it.
The Piripkura numbered around 20 people when FUNAI first contacted them in the late 1980s. After contact they returned to the forest. Since then, contact has been re-established with three members of the tribe, but no one knows if there are any more survivors.
In 1998 two Piripkura, named Mande-í and Tucan, walked out of the forest of their own accord. One of them was ill and was hospitalized, but both later returned to the forest. Rita, the third known Piripkura, has married a man from another tribe.
Mande-í, Tucan and any surviving relatives are in great danger as their land is constantly being invaded by illegal loggers. The loggers have purposefully blocked the Indians' traditional paths in an attempt to force them to leave the area.
"The Piripkura's land must be signed into law and protected immediately, otherwise they will be wiped out. We do not know how many they are, but the annihilation of a tribe, however small, is of course genocide," said Survival's director Stephen Corry.
Mande-í and Tucan rely on what they hunt and gather. They do not make arrows, but use wooden sticks and a knife they found in the forest.
Piripkura is a nickname given by a neighboring tribe. It means 'butterflies', a reference to the Indians' custom of traveling rapidly over vast areas of forest.