The Open Frontier Zone
The open imperial frontier model is located at the other end of the spectrum (Anderson 1996; Martinez 1994; Parker 2002). It was characterized by fluid economic relations, wide acculturation and social integration, and even ethnogenesis. In this context, the frontier was not only maintained open, but, due to the marked levels of socioeconomic interaction, borderlanders progressively merged culturally. As a result, the frontier groups shared similar cultural values and traditions. Spatially, this kind of frontier took the form of a broad zone of interaction with minimum imperial facilities.
Because the imperial presence was restricted, border populations were important intermediaries and imperial representatives, becoming central to the functioning of frontier exchange networks. As middlemen, they had a key role in managing the few imperial facilities and promoting the annexation of outer groups into the imperial economy through kinship, marriage, and trade relations. Depending on the levels of integration, ecological conditions, or social complexity, this culturally porous frontier might have been densely or lightly populated.
Although conceptually arranged along a continuum, these frontier archetypes did not necessarily entail successive stages of development. Ancient empires might have encouraged preclusive frontiers to later develop into broad and open frontier zones. On the contrary, some empires might have delineated open frontier zones, which due to increased interregional conflict, later evolved into more closed perimeters. Therefore, whether territorial or hegemonic in orientation, the political economy of the core did not necessarily echo the dynamics of the more distant frontiers. It is also likely that in antiquity there were additional variations not recorded along the frontier continuum—particularly if one considers the multifaceted historically contingent conditions leading to the development of ancient empires. Thus, the ideal types discussed here should be considered abstractions of a complex reality, although, admittedly, useful heuristical models to contrast with archaeological data.