Ordinarily, it takes place between strangers, even enemies.
Let us begin with the Nambikwara of Brazil. They would seem to fit all the criteria: they are a simple society without much in the way of division of labor, organized into small bands that traditionally numbered at best a hundred people each.
Occasionally if one band spots the cooking fires of another in their vicinity, they will send emissaries to negotiate a meeting for purposes of trade. If the offer is accepted, they will first hide their women and children in the forest, then invite the men of the other band to visit camp.
Each band has a chief; once everyone has been assembled, each chief gives a formal speech praising the other party and belittling his own; everyone puts aside their weapons to sing and dance together—though the dance is one that mimics military confrontation.
Then, individuals from each side approach each other to trade:
If an individual wants an object he extols it by saying how fine it is. If a man values an object and wants much in exchange for it, instead of saying that it is very valuable he says that it is no good, thus showing his desire to keep it. “This axe is no good, it is very old, it is very dull,” he will say, referring to his axe which the other wants.
This argument is carried on in an angry tone of voice until a settlement is reached. When agreement has been reached each snatches the object out of the other’s hand. If a man has bartered a necklace, instead of taking it off and handing it over, the other person must take it off with a show of force.
Disputes, often leading to fights, occur when one party is a little premature and snatches the object before the other has finished arguing.