There has, for a long time, been a perception that 'Germanic' barbarians (the Vikings, Saxons, Goths, etc) were naturally more violent than their 'civilized' neighbors, and you don't have to look very far to find books that support this interpretation (for example, Ward Perkins' Fall of Rome and the End of Civilization). The argument usually has a few common themes. Barbarians were envious of Roman luxuries, and wanted to take them for themselves (but, once they did, these luxuries made them soft and weak; or else, having taken these luxuries, they didn't know how to maintain them and it all fell apart into squallor). Barbarians were simpler, purer, less constrained by the trappings of civilization (this is the message in both Vikings and The Last Kingdom). Barbarians were more democratic, and hence military service was a duty of all free men, so - unlike the civilized Romans - all barbarian men learned to fight, and were buried with their weapons when they died.
These ideas go back really deep into the historiography - all the way back to Roman authors, actually, who loved to use the barbarians as a convenient rhetorical tool to highlight problems in Roman society. Many Roman authors (Tacitus, most famously) portrayed the barbarians as being less cultured, and yet - living closer to the natural state of man, unencumbered by the distractions of civilized life - also possed of the virtues and character traits that Romans used to pride themselves on. Until they got rich, until they got soft, until they forgot their roots. The barbarians, Tacitus wrote, were naked heros with honest laws, who served in their armies, were equal and free, and basically looked like charicatures of old Roman heros straight out of storybooks.
The flip aide of this positive portrayal was the violence. Barbarians, Roman ethnographers wrote, were jealous of Roman life, and wanted to sweep across the frontier and take a piece of it for themselves. The only thing holding them back was the Roman army (so pay your taxes, the emperors reminded their subjects!).
For years, scholars took this language at face value. In Germany, in particular, the idea that the ancient Germanic barbarians had always had manly, martial qualities that the Romans were afraid of was really useful. During the Reformation, protestants used this historical conflict to justify their separation (and superiority) to Rome. As the German states unified in the ninteenth century, the idea that all German people share dcommon ancestors whose fierceness brought the Roman empire to its knees was used to encourage a sense of pan-Germanic identity across the many separate kingdoms Bismarck sought to bring togeter into a sile country. The Nazis saw, in this history, proof that their ancestors had an evolutionary advantage: Germans had always been better at making war.
Outside Germany, the trope of warlike zgermanic barbarians was useful, too. In England and America, it fed the emergence of the White Anglo-Saxon Protestant identity, which saw the modern success of white English-speaking democratic countries as being rooted in the free and warlike peoples who had replaced the Roman empire. Burials of men with weapons, from the early middle ages, were taken as evidence of these warlike ancestors, and school children in Britain began to learn about Hengist and Horsa, the mythical Saxon warlords who supposedly conquered Britain in the fifth century, and laid the foundations for the island's unique genetic and cultural heritage.
This all broke down with WWII. After the war was over, notions of ancient and warlike Germanic conquerors who had violence in their very blood and ancestry was incredibly...problematic. And for the first time, people began to start questioning what, precisely, was up with the way that Romans had talked about barbarians.
What we've learned is that the barbarians were no more or less violent than anyone else in antiquity. In fact, ancient violence was really centered inside the Roman empire whose massive 400,000 man military drawfed, even in late antiquity, anything that existed beyond its northern frontier. Barbarians traveled south into Roman territory to serve in this army, and returned home once they had retired to the small farming villages where they grew up, bringing treasure and stories of war that would have been exotic and utterly unlike the small-scale violence that happened between the disparate and scattered settlements if northern Europe. Near the Roman frontier, these small settlements got bigger: men who had friends in Rome grew wealthy, and used this wealth to set themselves up as kings, uniting smaller settlements together into larger tribes. And some of these tribes eventually crossed into the Roman empire, becoming units in the Roman army in the century before the western empire's fall. But can we really say barbarians were more warlike than Romans, when they organized into these armies in response to a demand for soldiery by the empire itself?
The current view, which is not undisputed but, nevertheless, has become something close to consensus, is that the 'warlike barbarian' was an invention of the Roman state. The idea that barbarians were violent was politically useful to the Romans: it gave them a boogeyman across the frontier that could be used to scare people into paying their taxes and supporting the army. And actual barbarians often learned violence at the hands of the Roman army, in which they served. The barbarians tribes that invaded the Roman empire were products of interactions (economic and political) across the frontier, which allowed local big men to amass enough wealth and power to organize barbarians kingdoms where, before, something closer to anarchy had existed, and these kingdoms were warlike because the Romans paid them for their military service.
And this idea of the warlike barbarians didn't stop being useful after Rome fell. Up until the recent past, myths of pagan Germanic warriors, burning down civilization and proving that noble savages have something that soft, civilized Christians had forgotten, have been socially useful. Shows like Vimings, which portray the Christians as corrupt, scheming, civilized, and soft, vs. the primitive saveragery and nobility of the barbarians northerners, are just recycling this ancient trope.
Further reading:
Guy Halsall, Barbarians Migrations (2007)
Guy Halsall, 'Two worlds become one' (2014)
Philipp von Rummel, 'The fading power of images' (2013)
Sam Lucy, The Anglo Saxon Way of Death (2000)
Michael Kulikoswki, Rome's Gothic Wars (2006)
Krebs, A most dangerous book
The phrase "Barbarian Societies" is pretty loaded here and makes it extremely difficult to answer the question - I don't know what societies you mean.
I'm going to go out on a limb sand say that by "barbarians" you mean nomadic and/or travelling peoples who interact with settles societies around them. My background is Medieval History and the time that surrounds it, and in these periods there are two major areas that seem to keep on spitting out nomadic and/or mobile people who are pushing into settled people's societies - the Eurasian Steppe and Northern Europe. These two places are interesting because they share two important features - geographic isolation and somewhat limited resources. In Northern Europe isolation came from dense forest and other geographic features that can separate peoples from each other. On the Steppe the huge distances and sparse terrain separated peoples from each other. In Northern Europe the heavy soil made agriculture difficult prior to the invention of the heavy plough, limiting resources - in the Steppe the relatively arid climate limited the ability to farm.
It seems as though those conditions make for some unique sociological development - populations that can go into huge booms because resources are only somewhat limited, and different groups of people that share a material culture but have no kinship relationship to each other. This combination produces situations where there is frequently a need to move because of population pressures, and one where it is easy to form adversarial relationship with each other because there is limited perceived cultural connection between groups. So the areas that produce "barbarians" often also select for people who can hold their own in fighting. These areas create a situation where there is a constant "pressure," pushing groups from the interior of the area to the outside, where they come into contact with settled peoples.
This creates something of a selection bias - the "barbarians" who are coming into contact with settled peoples are often fleeing more powerful neighbors, trying to find a new, less overpopulated homeland, and moving with their entire population. This combination meant that any "barbarian" society that came into contact with a settled one would almost always have military prowess as important to survival. Additionally, because these were all mobile peoples, the entire population could be warriors as needed, so there was no tradeoff of conducting war. In settled societies if you took someone from a farm to fight you were reducing the wealth of your nation, for nomadic societies you could hunt one day, go to battle the next, then milk your horse on a third day without any negative impact to your society.
So yes, there were factors that made peoples we commonly think of as "barbarians" more martial - or at least they had more martial capacity as a percentage of their population. But this doesn't mean they were necessarily violence in a wanton or random way - the Mongols were known for having incredibly strict discipline, for instance, and a code of laws that opened up east-west trade routes for the first time.
I feel as though this answer might be rambling at this point but it really is too broad of a question to give a super-coherent answer to. "Barbarian" could refer to Scythians in 900BC or Mongols in 1200 AD, Vikings in 800 or Goths in 400. But I hope I've outlined some of the forces acting on nomadic peoples as they came into contact with settled ones, and how that could lead to societal forces in favour of martial capacity.
Quite frankly, I've chosen to study premodern violence in part as a response to my own experiences of violence in the modern world. There are—or at least should be—pressing concerns about how we use violence, coexist with violence, and even seek out and consume products created through violence (e.g. blood diamonds).
The current ways we talk about the world, however, often focus on abstract and dehumanized metrics like the GDP or the Dow Jones Industrial Average. These discussions take up an inordinate amount of time on the nightly news, somehow missing altogether the human dimension of suffering that allows me (and others) to live in a world of certain privileges.
TLDR I study barbarian violence because I find it challenging to examine violence in today's societies (including my own). I hope that my studies, by stepping outside the ways in which we are comfortable in dealing with the contemporary world, will help us reassess contemporary society and right some of the wrongs that we ourselves are causing.