There weren't. The Greeks had a legend about a tribe of warrior-women who lived in the forest and were known as the "Amazons", and when the Spanish first found

There weren't. The Greeks had a legend about a tribe of warrior-women who lived in the forest and were known as the "Amazons", and when the Spanish first found what we now know as the Amazon forest the natives tried to fight them off. The spanish conquistadores were so impressed by the fact that the indigenous women fought together with the men that they started calling the place the "forest of the Amazons", after the old Greek myth. The name stuck. But there was never an actual tribe called the "Amazons".