Prior to the third century A.D., two broad Roman conceptions of frontiers proliferated and competed: an imperial ideology of rule without limit coexisted with very real and pragmatic attempts to define and defend imperial frontiers. But from about A.D. 250-500, there was a basic shift in mentality, as news from and about frontiers began to portray a more defined Roman world—a world with limits—allowing a new understanding of frontiers as territorial and not just as divisions of people. This concept, previously unknown in the ancient world, brought with it a new consciousness, which soon spread to cosmology, geography, myth, sacred texts, and prophecy. The “frontier consciousness” produced a unified sense of Roman identity that |