On the day that the Conquistadors demanded that they surrender and pay tribute to them thousands of Jivaro came out of the jungle and massacred all but a few of the Spanish present.
By the 1950s their houses were designed with fortifications to defend against gunfire, even among friends firearms were at the ready during every visit. A visitor would expect his host's wife to eat from the same bowl of food before he did, to reduce the chance of being poisoned.
and american indian tribes were not environmentally friendly or peaceful either.