On Migration Events
We are re-sending this historical "long view" of migrations by British Museum curator Rupert L. Chapman III, Ph.D. because deportation arrests will start the moment Trump is sworn in.

One of the phenomena that recurs periodically throughout recorded history—which is to say, over the period from around 2500 BCE to the present—is mass migration. In the past, these events have been recognized primarily from their effects, from the comments made by denizens of established states upon the arrival of large groups of non-locals all at once. Migrations known from records from widely different regions have given rise to the designation Migration Ages. One of these ages affected roughly the last 200 years of the Western Roman Empire, from the 4th to 6th centuries CE.
Only in the last few decades has it become possible to study the causes of such migration events. The study of Arctic ice cores becomes increasingly sophisticated—as does the study of geophysical phenomena, such as the frequency of icebergs, as revealed by the deposits of boulders and other glacial debris on the ocean floor. These, coupled with tree-ring sequences, has made it possible to track and date palaeo-climatic events with increasing accuracy and detail. Also, advances in the study of ancient DNA are yielding the possibility of studying ancient outbreaks of infectious disease from human remains.
What these groups desired was peaceful admission to the Empire—to settle within it and even to serve in its administration and defense. The migrants, whom the Romans … called “barbarians,” wanted nothing more or less than to become Romans.
The result of all of this is that the study of migration events can now be extended back to well before the advent of written history. Historical examples can be examined with greater precision to reveal their causes, which are usually multiple and complex, positive feedback systems in which one factor (for example, climate change) affects other factors (for example, agricultural productivity). These, in turn, affect the health of populations and thus can lead to outbreaks of infectious disease.
In a purely scholarly sense, there is much to be learned from the causes of the present world-wide migration event, which should lead to policy changes which could mitigate the causes and reduce the necessity for the migrations, as well as their effects. Whether such positive policy changes will be made remains to be seen. If there is anything which the historical examples can teach us, it is that attempts to create a solid and impermeable barrier to such migration events are usually completely futile. For example, Egypt managed to fend off the Euro-Anatolian migrants at the end of the Late Bronze Age, but only just, while the rest of the Near East was simply rolled over by the wave. Adaptation to the incomers, although it always takes time and results in a changed economic, social, and political reality, works.
It is also worth noting that in recent decades, the ongoing study of what is perhaps the best-known such event, the one mentioned above affecting the Western Roman Empire between the 4th and 6th centuries CE, was not, as once thought, a case of vast hordes of people from outside the Empire seeking nothing but destruction and loot. Rather, it was a case of peoples from beyond the boundaries of the Empire being pressured to move into it by other migrant groups from farther (and farther) east. What these groups desired was peaceful admission to the Empire—to settle within it and even to serve in its administration and defense. The migrants, whom the Romans (in the great Greek tradition of self-perceived cultural superiority) called “barbarians,” wanted nothing more or less than to become Romans. It is interesting to note that the term barbarian originally meant people who didn't speak a real language, which is to say Greek—a category which, of course, included the Romans.
In the end, the Western Roman Empire disintegrated, not because of the migration event, but because it had ceased to be a dynamic and administratively effective organization and had become sclerotic and administratively ineffective. The “fall” of the Empire was more the failure of the central administration as control became a matter of who controlled the most powerful block of armed followers rather than who had the most support or was the best administratively. As the central administration disintegrated, what remained were local administrations, far less wealthy and much less effective—but just effective enough to maintain order locally. For the next thousand years, these local administrations would be neither as prosperous nor as generally peaceful as the Roman Empire had been—despite the Empire’s frequent wars over the throne.
Rupert L. Chapman III, Ph.D., Devon UK
I love the etiology of the word "barbarian"! My father was a professor of Sociology for decades, first at the University of Michigan and then at the University of North Carolina. (His name was Gerhard Lenski.) I remember him telling me, many decades ago, that the "fall of the Roman Empire" was primarily caused by the mass migration of people who spoke many different languages -- less so the fact that they also brought with them a myriad of different religions and cultures. He felt that "the center could not hold" (to quote Chinua Achebe, well actually William Butler Yeats, to be accurate) as a result. He said that the most important thing, in his opinion, was that English be THE language of the United States, and no other language should be allowed in schools or other public places. Interestingly, when his mother was a child (born in 1887), her mother had immigrated from Germany. Her husband was from a German family which had immigrated generations before, but still spoke German. Only German was spoken in the home. When my Grandma started school, she had no idea what was being said. The teacher went to their house and told my great-Grandfather (great-Grandmother, of course, couldn't have understood her) that the children were to speak ONLY English at home; otherwise they could never become fluent in the language. [A parallel is with one of my great-Grandmothers on the other side of the family. She, too, was a German immigrant, married to a man whose family had come to the United States from Germany 100 years earlier. Her children were therefore fluent in English. However, when WW I began, she was warned to STOP speaking German in public because Germany was our enemy. According to one of her daughters, she never spoke German again.]