In order to understand how indigenous communities in the Amazon make decisions regarding territory and reach agreements regulating use of natural resources in the face of extractive economies, an experimental ethnography was carried out involving design and implementation of a serious board game. "Managing the Territory" is a thematic group game which is not dependent on chance, but rather invites players to discuss dilemmas, make decisions, and develop agreements regarding economic activities involving use of natural resources to be carried out in their territory, including extractivism. This ethnography discusses players' commentaries that emerged during the game as well as community decision making in the face of potential social and ecological impacts of extractive activities. The actions of the game that promoted developing agreements among players led them to reflect on topics in need of community decision making regarding regulation of their territorial resources and to discuss their differences of interests. In some cases, the potential influence of extractive economies led players to take action to establish, revoke, or modify a formal territorial management agreement, and in others to restore or revoke an informal traditional pact. Players' commentaries allowed for inferring principles of indigenous territorial management related to sufficiency and reciprocity, as well as informal territorial management pacts, that explain the rationales according to which they regulated the territory during the game.