I've looked into this many times.... and there always seems to be a bit of a 'but'... as in 'un-contacted but'. Meaning... even the most remote tribes... like those in New Guinea, are 'aware' of other civilizations and have made 'some' type of contact.. even it said contact was hostile, like the Sentinelese Tribe.
Remember our thread about "Ishi"... the last North American Native who, as the only member of his tribe remaining, came out in 1911? Very interesting if you haven't seen the documentary.
