Using archaeological and literary evidence, Burns describes relations between the Roman Empire and "barbarians along its frontiers in Western Europe, across a span of 500 years."
Romans believed themselves superior to their barbarian neighbors. They looked upon their own civil wars as grave affairs while "making light" of the endemic warfare among the barbarians.
Rome was interested in peace and stability on its borders. Barbarians were threatening and invading each other, including those societies with which Rome had alliances. In addition to protecting its barbarian allies, Rome pressured these allies to limit their warfare.
Trade between Romans and barbarians was ubiquitous. The trading included Celtic peoples, whom archaeologists have found evidence of having a large quantity of Roman goods, suggesting ongoing trade. In the second century B.C.E., in southern and central Gaul, Celts systematically produced "highly refined" iron products, and Roman traders purchased Celtic iron wear for resale.
The empire's barbarian neighbors were hierarchical and with wealthy elites. Judged by buried artifacts and a few observations in Roman literature "Gauls almost everywhere were governed by elite families, which were bonded together through marriage and service within the community and region."
Burns writes that "Caesar regarded it as quite natural that every Celtic community had a few families vying for political power and that one or more would come forward seeking his aid."
According to Burns, "Rome offered native elite families powerful support" vis-à-vis their own people "to a degree never possible before Roman intervention."
Rome helped the barbarian elites without interfering in their religious matters. An exception was Rome's attempt to extirpate the Druids, who were actively hostile to the Romans and viewed by the Romans as a threat.
Rome was not eager to intervene militarily against its barbarian neighbors because such interventions were expensive and Rome was not infinitely rich. And there was no guarantee that even a successful war would not "lead to a return to less secure and predictable barbarian leadership rather than the reverse."
Peaceful migrations of barbarians into the Roman Empire did occur, and the migrants became Romanized. During Rome's decline in the 200s and into the 300s a "composite society," a mix of Romans and barbarians, was forming on the empire's frontiers. Barbarians on the frontier formed new confederacies and hired themselves out as special units within Roman armies. And occasionally these barbarian warriors were urged by one Roman general to plunder the allies of a rival Roman general.
Labor was in short supply around the military camps on the empire's frontiers, and Gothic (German) barbarians served as "day laborers, soldiers, female companions and wives."
Civil war within the Roman Empire was accompanied by an increase in demand for barbarian soldier-recruits. By the 400s it was common for Roman generals to have barbarian ancestry.
About the Christianity of the barbarians, Burns writes that before the year 400, Christianity "was of little importance to the barbarians" compared to their pagan practices. Between the years 350 and 400 Christianity was the religion of only a handful of Goths. Despite efforts by Ulfilas, the Germanic Christian evangelist, there was no organized Gothic Christian community north of the Danube. For the barbarians, Christianity had been the faith of Roman emperors. Only after they entered the Roman Empire did the Goths adopt Christianity.