Reading the diary of Francisco de Orellana, the first European explorer to travel down the Amazon from Peru to the Atlantic, he wrote of numerous large villages and highly organized societies. All of them tried to kill him and his men. He was attacked by a tribe of very tall, powerful female archers which is how the river got its name.
IIRC, he started with about 500 men plus horses, war dogs, and many porters. IIRC, he made it to Trinidad with about 20 survivors.
British man walks entire Amazon river in 2 years
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After they were welcomed in one Indian community in September 2008, the leaders offered to radio ahead to the next village for permission for Stafford and Rivera to walk through their territory.
"The response came back crystal clear. If a gringo walks into their community they will kill him," Stafford wrote on his blog at that time.
He decided to plan a route around the village, but he was still captured by Indians from another village and taken to their leaders.
After being dressed down and having their possessions thoroughly picked over — only a machete was confiscated — Stafford and Rivera's repeated explanations of the point of their expedition won over the Indians.'