Well, Jorvik simply means “earth bay” so it sounds like the kind of name you’d give a location from the geography. Northern England is full of names that are just a descrition of what you see in Norse.
Anyway, this thread was started in 2014, and beginning in 2015 there has been an absolutly fantastic amount of information incoming from advances in the genetic analysis of ol remains. So for those who are interested:
After the Ice Age, the area that would become the British Isles was populated by the people called the Western Hunter-Gatherers (WHG). These people lived in all of Western Europe, and at the time the British Isles were not islands. These people were hunter gatherers as the name implies, and seem to have had a very low population density.
Agriculture arrived in Britain about 4000 BC, a 1000 years later than on the mainland. It arrived with a people known as the Anatolian farmers, as they were a population group that seems to have expanded from an Anatolian origin for about 2000 years previously. The particular ones arriving in Britain seems to share genetic affinities with the population then in Iberia. (caution: many areas lack samples from this period). Also some much smaller affinities with the Danubian farmers.
There are hints that they started out in South Wales. Population replacement of the WHG in Wales was total. No trace of the WHG genetics can be detected in individuals from Wales. The rest of Britain picks up some little WHG ancestry but remain 90% or more farmer genes. The percentage of WHG genes did not change over time after this, the initial small amount of mixing was all there was.
Source: Population Replacement in Early Neolithic Britain (preprint)
Personal note: Since farming was a millennium late in getting to Britain, it would have been a more mature technology and better adapted to the climate when it came.
About 4 500 years ago, another people arrived in Britain from continental Europe. DNA shows greatest affinity with people living in and around the Nederlands at the time. They were called the Bell Beakers. A bit of a misnomer since Bell Beaker in other places were a culture that spread across many different people. But when it arrived in Britain, it was carried by one people, with ancestry mostly from the steppes north of the Black Sea and the Caspian. Indo-Europeans.
Their replacement of the Anatolian farmers was even heavier than the previous population turnover. Estimates are a minimum replacement of 93 %.
Source: *The Beaker Phenomenon and the Genomic Transformation of Northwest Europe, *2017.
There were some fluctuations in ancestry for a while, indicating that some local populations held out for some time. Particularly in areas such as southeastern England, with very fertile land.
There is a theory that this migration consisted of people speaking a very early version of Celtic. If so, there was absolutely a genocide and it was nearly total. However, I think most researchers favor a later entry for Celtic. This would not seem to be associated with such massive population turnovers at least.
For visualization purposes, the Western Hunter-Gatherers in Britain had dark black skin, black hair and blue or green eyes. The Anatolian farmers have a surviving group with a very high degree of genetic continuity, the people of Sardinia. They probably looked nearly identical except less tanned. These were the megalith builders, who built Stonehenge. Otzi the Iceman belonged to this group. Strangely, they carried on some of the building traditions among other in the form of barrow graves.
The people who replaced them probably looked similar to todays western and central Europeans. Sort of Danish with a bit of Polish. That is not to say that they were Danes and Poles but that this gives some idea what they looked like.