So the egalitarian tribe in the middle of the Amazon (and the thousands like it) had a message available to them? They had the internet?
I would suspect the answer I gave would just be a source of amusement. God loves laughter, so happy to give an answer.
I am not aware of Amazon tribal beleifs, so can not comment on those ancient traditions. But the American Indian and Australian Aboriginal who are also ancient cultures, did indeed have guidance from God.
lets use Krishna as an example, as Krishna is closer to home for you.
Krishna gave a Message from God, (many beleive Him to be God) That Message given to a certain audience, is at the same time Universal in its penetration and brings about a new heaven and a new earth.
Receptive souls around the world and in other worlds of God are influenced by that outpouring of Spirit. Thus in an American Native Tribe, the Amazon or in a far away Australia Aboriginal Tribe, a receptive person will be inspired to offer a new vision, or a new path for their people. This inspiration coming from the Message of Krishna.
God gives what enables us to progress to the next level of understanding. I am sure you can see glimpses of simularities in what you have embraced. (Added that for fun, I need a laugh to)
Now imagine the power of a message given by a Messenger that is destined for a world Audience and the influence it exerts.
Peace be with you always.