Inter-territorial economic cooperation is a special phenomenon, the study of which economists, jurists and historians have started relatively recently. Meanwhile, the system of institutions regulating relations either competition or cooperation between regions or between municipal formations took shape in Russia during the decades of the implementation of modern economic reform. The article reveals the features of the formation of regulatory bases of interterritorial interaction in the context of both hierarchical and heterachical institutions. Particular attention is paid to such an informal institution as trust in interregional and intermunicipal relations. Hopefully the experience of interterritorial cooperation may be in demand in the Republic of Tyva.