It is the amount of interaction between social units that affects the character of a community or a society. Beyond this network of interchange are zones of diminishing exchanges between peoples. There are interchanges even across ethnic boundaries, however, and the character of these social exchanges defines the limits. Thus, even if there are factors that divide the various peoples of the Philippines into distinct ethnic groups, there still exist social exchanges between them, if not in terms of exchanges for marriage, then exchanges for goods or for social services. Trade is one of the strongest bases for reciprocity among groups and the sociologically acceptable means of penetrating social boundaries. For instance, Maranao merchants range far into central Mindanao and Central Philippines in their trading forays. The Ifugao go from the Cordilleras to the Cagayan Valley to trade for animals. Peoples from the lowlands, on the other hand, depend on the highlanders for forest products.

Ethnic boundaries, however, are continually maintained although transactions take place through them. Interchanges among the different Philippine ethnic groups are not entirely harmonious as frictions develop even among the best of kin. When kin groups are involved, friction escalates in accordance with the number of participants and intergroup conflicts taking place. More often than not blood flows which must be balanced by each contending side. Headtaking thus developed as a social mechanism among the Ilongot, for instance, for minimizing conflicts and retributions. And peace pacts are forged between conflicting groups as among the Kalinga to ensure peace, further enforced by the establishment of ritual kinship and blood brotherhood, as in the case of the Tagbanua of Palawan. Slowly, however, the civil government structures radiate even to the hinterlands to slowly redefine traditional social controls that integrate the different ethnic societies.