Interesting fact:

It turns out a region of the Amazon Rain forest, thought to be uninhabited, may once have been home to over 1 million people! Geographers from the University of Exeter have been using satellites to study this notoriously tricky region, and they’re findings suggest that, prior to the arrival of Europeans, huge swathes of the rain forest were home to tribal communities that may add up to well over a 1 million members in total.