The Porous Imperial Frontier
Frontiers could also take the form of graded and porous margins, particularly in cases of hegemonic control (Anderson 1996; D’Altroy 1992; Martinez 1994; Parker 2002). In this situation, the frontier was more likely to display less emphasis on imperial military control. Instead of focusing on defense only, frontier installations also served to promote economic exchange and the selective integration of native populations. Because economic relations were more fluid, frontier facilities were often located in valuable areas linked by roads and economic corridors. Consequently, porous frontiers were the setting for relatively fluid social relations, mutual acculturation, selective patron-client relations, and economic interdependence (Eadie 1977:57; Elton 1996; Parker 1998; Whittaker 1994).
Since relations between the empire and the local population were rooted in socioeconomic interaction, military control was vested primarily in local populations. They became valuable allies and supernumerary members of the state’s defensive network (Eadie 1977:58). As a result, imperial forts and garrisons were often limited in number and acted chiefly as visible deterrents in strategic zones. Considering that installations were built and manned with local garrisons, this materialized in the blending of imperial and local features in the architecture and associated material culture. This inexpensive strategy was pursued when the frontier zone was not characterized by heavy economic extraction or administrative investment, the external population consisted of highly fragmented “nuisance” groups rather than powerful or threatening opponents, and ecological factors prevented the easy transplantation of core economic patterns.