The Preclusive, or Hardened, Frontier
The preclusive, or hardened, frontier often acted as a defensive barrier. Hence, the construction of a defensive perimeter was designed to prevent any form of interaction between inner and outer populations. Because the imperial frontier was deliberately closed, there was an absence of a transitional zone; as a result, the borders sharply demarcated internal and external spaces (Anderson 1996; Hudson 1985; Martinez 1994; Parker 2002). As a barrier, the frontier also served to separate two political organizations and cultural traditions. In times of heightened conflict or sustained warfare, closed frontiers acquired particular importance. Crossing such a barrier might imply the passage to dangerous, forbidden lands.
Closed military perimeters often materialized in the construction of hardened defensive barriers along long stretches of land. Because any form of social interaction was prevented, these spaces were clearly delimited by the presence of separate and different types of cultural material assemblages, residential settlements, and public architecture on each side of the frontier. Arguably, examples include certain frontier segments along the Great Wall of China in the Dynastic era or imperial Rome. Yet the maintenance of completely closed frontiers for extended periods of time rarely existed in antiquity. More likely, this kind of frontier reflected more the vision and policies of the rulers than the actual situation experienced by the frontier communities.