They came via the North Sea: According to a study by a 70-strong research team, masses of people, especially from northern Germany, streamed into England in the early Middle Ages. And there the immigrants were apparently largely integrated very well and very quickly.
After the end of the Roman Empire, England experienced a massive upheaval in its population within a few centuries. According to a study, this was due to the continuous immigration of Anglo-Saxons from the continental North Sea region in the early Middle Ages: from parts of today's Denmark and the Netherlands and above all from northern Germany - i.e. Schleswig-Holstein and Lower Saxony. The immigrants settled mainly in the south and east of England and were often surprisingly well integrated into society, as an international research team writes in the journal "Nature".
So far, the population development in the British Isles in the 1st millennium AD has been controversial - especially after the end of the Roman Empire in the late 5th century. The writings of the scholar Bede Venerable, written in the 8th century, are considered to be the most important historical source, but they leave many questions unanswered.
Archaeological finds as well as place names already indicated a major influence of the continental North Sea region and above all the North German Elbe-Weser region. The team led by Stephan Schiffels from the Max Planck Institute for Evolutionary Anthropology in Leipzig cites a few examples: such as the pit houses typical of northern Germany - i.e. buildings around a pit embedded in the ground -, decorations of objects with animal patterns or burial customs.
So far, however, both the magnitude and the circumstances of immigration in the Middle Ages - migration or invasion - have been unclear. The research team of about 70 investigated these questions by analyzing the genomes of 460 people buried between the years 200 and 1300 in England, Ireland, Denmark, the Netherlands and Germany. Almost 280 of these lived in England, particularly in the period 450-850 AD.
The results illustrate the extent of immigration in the early Middle Ages: In the Bronze Age - i.e. around 3000 years ago - the proportion of the population of northern European-continental origin was still around 1 percent. During Roman times, the proportion probably rose to around 15 percent - but the value is very conditional, because it is based on the analysis of only seven people.
It is interesting that people of Anglo-Saxon descent were not uncommonly part of the upper class of society at the time: men who were buried with weapons were similarly of Anglo-Saxon and local origin. Women with a migration background were even more often buried with grave goods, especially jewelry such as brooches and pearls, than women of native origin.
However, there are also clear differences between individual sites in the east of England: "We discovered some significant differences in how this migration affected the communities," says archaeologist Duncan Sayer from the University of Central Lancashire. "In some places we see clear signs of active integration between natives and immigrants, as in the case of Buckland near Dover or Oakington in Cambridgeshire. However, in other cases, like Apple Down in West Sussex, people with immigrants and those with natives have been mixed up Ancestors buried separately in local cemetery."
Regardless, the team concludes in the journal Nature that during the early Middle Ages, eastern and south-eastern England, along with the continental North Sea and western Baltic Seas, formed a genetic continuum - that is, a fairly uniform area in terms of population.
During the analyzes the researchers also found many people of French descent in the south-east of England - although not nearly as much as those of Anglo-Saxon origin. The team suspects that this immigration from Western Europe came later. In Wales, Scotland and Ireland, on the other hand, there were hardly any traces of continental immigration in the Middle Ages.
"Our results provide overwhelming support for the view that the formation of early medieval society in England was not simply the result of small-scale elite migration, but that mass immigration must have played a substantial role," the team writes.
At that time the Anglo-Saxon influence on the population seems to have reached its peak. Today, around 40 percent of the genome of modern-day Englishmen still derives from Anglo-Saxon ancestors, while around 20 to 40 percent of their genetic heritage comes from more western regions - possibly modern-day France or Belgium.