Too good to be true, of course. As the Guardian explains:
[I]t has now emerged that, far from being unknown, the tribe's existence has been noted since 1910 and the mission to photograph them was undertaken in order to prove that 'uncontacted' tribes still existed in an area endangered by the menace of the logging industry.
The disclosures have been made by the man behind the pictures, José Carlos Meirelles, 61, one of the handful of sertanistas – experts on indigenous tribes – working for the Brazilian Indian Protection Agency, Funai, which is dedicated to searching out remote tribes and protecting them. ...
For two days, Meirelles says, he flew a 150km-radius route over the border region with Peru and saw huts that belonged to isolated tribes. But he did not see people. 'When the women hear the plane above, they run into the forest, thinking it's a big bird,' he said. 'This is such a remote area, planes don't fly over it.'
What he was looking for was not only proof of life, but firm evidence that the tribes in this area were flourishing – proof in his view that the policy of no contact and protection was working. On the last day, with only a couple hours of flight time remaining, Meirelles spotted a large community.
'When I saw them painted red, I was satisfied, I was happy,' he said. 'Because painted red means they are ready for war, which to me says they are happy and healthy defending their territory.' ...
Survival International, the organisation that released the pictures along with Funai, conceded yesterday that Funai had known about this nomadic tribe for around two decades. It defended the disturbance of the tribe saying that, since the images had been released, it had forced neighbouring Peru to re-examine its logging policy in the border area where the tribe lives, as a result of the international media attention. Activist and former Funai president Sydney Possuelo agreed that – amid threats to their environment and doubt over the existence of such tribes – it was necessary to publish them.