"The term originates from the Greek: βάρβαρος (barbaros). In ancient times, the Greeks used it mostly for people of different cultures, but there are examples where one Greek city or state would use the word to attack another. In the early modern period and sometimes later, Greeks used it for the Turks, in a clearly pejorative way. Comparable notions are found in non-European civilizations, notably China and Japan. During the Roman Empire, the Romans used the word "barbarian" for many people, such as the Germanics, Celts, Gauls, Iberians, Thracians, Parthians and Sarmatians."
When a fall of a culture happens, the blame for such is often cast upon the outsiders. However, the fall of any great empire or society has most often been from issues within and endemic to the society. Greed, hedonism, refusal to serve public duty, and other reasons are more often the cause of the fall. When people on the fringes of society or from a different society attack/invade or are involved in a war with the society, they are often called Barbarians. Julius Caesar himself faced many tribes of so-called barbarians and it was his victorious campaigns against them that caused his great popularity.
Those same peoples were the cause of the military fall of Rome. In Britain where the Romans had attempted to expand power by removing kings and queens and taking the land, the Icenii tribe revolted under the hand of Queen Boudicca and her daughters. They burned Londonium before their rebellion was put down. On the mainland Celtic tribes in Gaul, modern France were subjugated by Caesar, but Germania stood afar from the conquests, and from Germanian Celts were among those who caused the sack of Rome. But Rome's walls and culture had fallen long before.
Addiction to gladiatorial games, the use of slave labor, mercenary ranks filled in the Roman Legions, and more all hollowed out the culture's fortitude. They'd lost their will to fight for their own safety. The barbarians invading succeeded, but it was because they themselves were as hardy and powerful as the Romans who fought the Carthaginians, who had carved out their Republic had been. The pleasure seeking Romans 800 years after the Punic wars, of the empire, were fat, lazy and arrogant in comparison.
“In my own opinion, the average American's cultural shortcomings can be likened to those of the educated barbarians of ancient Rome. These were barbarians who learned to speak--and often to read and write--Latin. They acquired Roman habits of dress and deportment. Many of them handily mastered Roman commercial, engineering and military techniques--but they remained barbarians nonetheless. They failed to develop any understanding, appreciation or love for the art and culture of the great civilization around them.” J. Paul Getty, Billionaire
"History teaches us that when a barbarian race confronts a sleeping culture, the barbarian always wins."
Arnold J. Toynbee
Arnold Joseph Toynbee CH (April 14, 1889 - October 22, 1975) was a British historian whose twelve-volume analysis of the rise and fall of civilizations, A Study of History, 1934-1961, was a synthesis of world history, a metahistory based on universal rhythms of rise, flowering and decline, which examined history from a global perspective.
Alexander the Great
O [Roman] people be ashamed; be ashamed of your lives. Almost no cities are free of evil dens, are altogether free of impurities, except the cities in which the barbarians have begun to live...
Let nobody think otherwise, the vices of our bad lives have alone conquered us...
The Goths lie, but are chaste, the Franks lie, but are but are generous, the Saxons are savage in cruelty...but are admirable in chastity...what hope can there be [for the Romans] when the barbarians are more pure [than they]?"
In the early 1970s Marvel Comics restored the memory of Conan and Robert E. Howard's world of characters and adventures. First with Conan, then with tangent characters and stories, they created a wonderful print and color memory of the set of stories.
Not Conan, but the Celts versus the Romans, via Crossgen comics and Chuck Dixon. Sadly uncollected by Crossgen or Checker or Marvel since the end.