The Stone Age isn’t quite over — not everywhere. On North Sentinel Island in the Bay of Bengal lives a tribe of about 250 people, the Sentinelese, who have remained so hostile to contact with outsiders that their society is almost entirely free of modern influences.

They have no agriculture, subsisting through hunting, fishing and gathering plants. It’s not even clear whether they can produce fire without an external source like lightning.

The Indian government has made overtures by leaving gifts, but the warlike Sentinelese drove them off. Earlier this year, Sentinelese archers killed two fishermen who came too close to the island. Their bodies still haven’t been recovered — even a helicopter sent to retrieve them was driven off by arrows.