This study attempts an alternate look at what is sometimes a quick study of an ingrained “Roman aggression” placed in the opening chapter of a typical Roman history, re-evaluating the “us-them” element in Roman thinking during their primeval “homesteading” era, and some of the motived often imputed to tribal Roman culture that have been used to explain their expansion in Italy (and after). From the pomoerium, or spiritual/physical boundary of the farm or the community, the frequently cleansed and inspected line between the settled and peaceful homesteaded or urbanized place and the dangerous, unsettled outlands beyond, where potential raiders or enemies – hostes – and the spirit that animated them dwelt. Romans punctuated this boundary with shrines, openings (carefully guarded by archaic spiritual means) and, at key moments during the year, by religious activity intended to keep them safe. These activities and checkpoints are clues to the way Romans saw the boundaries, and may even correct some false impressions we have of important features in their urban landscape. The checkpoints of passage through this boundary between human community and outworld were gate-like temples (guarded by Janus) or a similar structure called a “iugum,” and both underlie the structure we today call a “triumphal arch.” Understanding how Romans (or archaic Italians) felt about community boundaries may help correct the image we have of this arch, and what it meant, and in fact our image of them. Early Roman boundary-passage customs use these artifacts for related forms of expiation, cleansing and pacification, a character shared by the treatment of defeated armies and in fected persons, even meaning in the triumphal procession, which had much more to do with cleansing the contagious guilt (or infected violence) of a returning army than it did with celebrating a victory. More than a century ago the Roman historian-anthropologist William Warde Fowler attempted clear modern perspectives on early Romans, aggression-defense, and their ideas of boundaries. This article is also a tribute to some of his key, forgotten insights. Keywords: ancient urban studies, Archaic Italy, Roman rituals, Roman anthropology, Roman aggression