The exchange of important commodities like fish, sago, and pots between communities speaking dozens of different languages was not a focus of anthropological research in Papua New Guinea until the 1990s. This book explores how more than 100 communities who speak nearly fifty languages from five unrelated language phyla interact by developing persistent relations known as "hereditary friendship." These relations provide everyone along the coast with fish, sago, and earthenware pots as well as many other useful commodities. By minimizing hostilities between and among different groups without invoking marriage, which is so important elsewhere in Papua, friendship relations brought harmony, peace, and basic commodities.