The Tlingit Indians were very civilised, and disliked fighting. Instead of declaring war on their enemies a tribe would simply send them presents and invite them to a party which was called a Potlatch.
The Potlatch was simply a great big party, lasting several days, with copious quantities of food and drink. The invited guests would be expected to bring presents, of a greater value than those which had been delivered with the initial invitation.
Within a specified time (usually a year) the invited tribe would have to throw a Potlatch party in return, and invite the original tribe. This tribe would have to bring presents which were of greater value than those which they had received at their initial party.
After the same time had again elapsed, the first tribe must throw another party, and the second tribe must again bring gifts but this time of a greater value than those they had received at the previous party.
This continued with gifts of ever greater value, until the value of the gifts was so great that one party was unable to exceed the value of the gifts they had received the previous time. They were then defeated and must surrender themselves to the other tribe.
A similar process may be observed in our society, between mothers at a succession of children's birthday parties.