Our society is run by a monetary economy and for us to consider providing for our needs in another way is simply gibberish. That being said, for all of recorded history until a few thousand years ago, we did provide for our needs in another way entirely.
Well, I wouldn't say that "our society is
run by a monetary economy"; I'd say that money is a tool we use to coordinate economic activity. And up until a few thousands years ago, "providing for our needs" translated to eking out a living through subsistence farming. Money evolved because it was useful. Again, small socially-cohesive groups might be able to get by without a system of explicit exchange based on money, but it won't work for a large, complex economy. The price mechanism is the most powerful and efficient tool we've discovered for coordinating the activities of huge numbers of people who may live thousands of miles apart and never meet. Something tells me that the laptop I'm using to type this comment on would not have been built if all of the people involved in its design and manufacture had needed to rely on a system of informal obligations created by reciprocal "gifts."
Therefore, the exchange that we saw between tribes was usually for reasons that wouldn't "compute" in todays society. For example, many tribes give offerings to other tribes in order to insult them by showing how powerful they are that they can then afford to give so much to the other tribe.
That computes just fine. If anyone would like to demonstrate their power (and my inferiority), they can do so at the following address: 1PjN1PegGNq9ERYvLi1Zg2HNTgWqneMMrT
(Remember, the more you send, the more bad-ass you are.)