Most people know that the DNA molecule carries the genetic instructions for building living organisms. It gradually mutates over time, so we can track human populations by looking for those mutations. It can be useful in telling us about the origins of population groups (such as Scandinavian people or Welsh people). Various studies have adopted different approaches. Some have looked at DNA retrieved from ancient human remains. This is referred to as aDNA. Others have looked at modern DNA. I refer to this as mDNA (not too be confused with miDNA or mitochondrial DNA). They each have their own advantages and disadvantages. If we are interested in what was happening in the past aDNA can look at the people who lived at the time. Unfortunately the remains available are quite scarce and are a by-product of archaeological excavations. Their availablity will depend on whether the remains were found in suitable environments, and on things like access to archaeolgical sites and the interests of the archaeologists. Modern DNA is more plentiful, but will depend on access to data, perhaps from medical sources, and the interests of the medical or other professionals involved.
There is a widely held belief that place names ending in 'by' were introduced by the Vikings. The corollary of that belief is that we know the extent of Viking occupation of England by mapping out the distribution of these place names. I know these views are widely held because Chat GPT believes it to be the case. I asked the following questions on 27th July 2026, "tell me why so many place names in the North of England end in 'by'?". The answer was, "… 'by' is usually a sign of Viking settlement …" I then asked, "How do we know where the Vikings settled in England?". In relation to the large numbers that are used to explain widespread settlement they said, "...These names are heavily concentrated in northern and eastern England, showing where the Scandinavian settlers lived in large numbers." The arguments can become circular, when used to support each other.
I am extremely sceptical of the idea that it was the Vikings who introduced Scandinavian language and place names into England. As I have argued in my other essays, there are many reasons to doubt it, for example, the primary written authority (the Anglo-Saxon Chronicle) makes no mention of mass migration. Moreover, there are many places in the Viking's Danelaw where Scandinavian place names are absent. This is also true of other Viking colonies abroad, for example, Normandy, Iceland and Ireland. When I started my studies Genetic research into the question was in its early days, but if there were evidence of Scandinavian occupation before the Viking age, it would be likely that it would be responsible for Scandinavian influences in England.
This essay looks at published genetic research into the origins of early medieval people in England. Studies have used both Ancient DNA and Modern DNA. I'll start with the most recent first.
This research looks at the troublesome question of the nature of the Anglo-Saxon invasion of England; whether it was a mass tribal immigration or a conquest by an elite who imposed their Anglo-Saxon habits on the local British. It is mainly based on aDNA, however there is also some cross checking of the results with older DNA and mDNA (Gretzinger 2022) , see references below and the linked Supplementary Information). Genetic material was retrieved from individuals found in the places shown in Figure 1 and listed in Appendix 1. The majority of sites were in the East or South with clusters in Cambridgeshire and Kent. Unfortunately there are significant gaps in the western half of England. Each individual’s DNA was analysed to identify the proportion of WBI (referred to here as “Celtic”) ancestry versus CNE (referred to here as “Germanic” and including Scandinavian) ancestry.
The authors report two methods used to identify likely European origins. The first uses a conventional statistical approach to analyse differences in samples. I simplify, but, they treated UK DNA as one sample and continental DNA as the other. They looked for differences in the corresponding bits of DNA between the two countries and looked to see whether those differences were statistically significant. The second method ("Locator") used machine learning to locate the region on the continent that is the likely source of UK DNA. Unfortunately they rather fudged the results by superimposing the results from the two methods on the same graph. To make it worse, they coloured the symbols red for both methods. I have recoloured the symbols from Locator as grey. Both methods suffer from a sampling deficiency, There appears to be only a single source of DNA in the homeland of the Angles (which proved to be statistically insignificant). The only statistically significant source of DNA on Jutland, the putative home of the Jutes, was adjascent to the rest of the Danish observations on the Islands ("insular Denmark"). . This leaves a data set that is essentially bi-modal (in two parts). It is difficult to understand how Locator interpolates origins on Jutland that are essentially absent. Nevertheless it produces genetic "origins" across the full geographical region from North Germany to the far South-West of Sweden, including predicted origins in the North Sea (the hatched line on my Figure 2). The more conventional statistical approach cannot even attempt to compensate for the missing data. It simply tells us whether, of those places in the continental data set, which ones were likely to have been the origin for the DNA found in the UK. What is particularly surprising is that both methods include places from the far north east of Denmark and into Sweden.
In England place names containing the element “by” are abundant in much of Lincolnshire, Leicestershire and Yorkshire (measured as a proportion of all place names). Their most likely origins can be inferred from their distribution in Scandinavia. Their scarcity in other North European Viking age settlements makes it likely that the English “by” place names are pre-Viking. This possibility is supported by the similarity between the “by” place name distribution and the distribution of likely sources of pre-Viking DNA in Scandinavia (my Figure 3). Clusters of both appear in North-East Zealand (near Copenhagen). Ie, the DNA evidence and the place name evidence support one another.
Another study, by Margaryan (see references below, 2020), examined ancient DNA in the North European Scandinavian world. As their title suggests, their main interest was with the Vikings. Like Gretzinger, there was some cross-checking of their findings with mDNA. Dissapointingly the title "Population genomics of the Viking world" is misleading. To quote, "Within the British Isles, it is difficult to assess how much of the Danish-like ancestry is due to pre-existing Anglo-Saxon ancestry,..." so, the people who used "by" place names might equally have been Angles and Jutes as Vikings. Accordingly, the paper isn't helpful in understanding the widespread origins of place names ending in "by" in northern England. Additionally the English sample was quite small, with only 442 people across all of Greenland and Europe. They show that it was, "individuals with Norwegian-like ancestry (who) travelled to Iceland, Greenland, Ireland and the Isle of Man ..." which could explain the absence of "by" place names earlier, but this still does not help us decide whether the "by" place name endings came with the Vikings.
Not only was the sample small, but it was not helpful in understanding Viking age settlements in England. Two were groups of Viking Age adult males, one from Oxford and the other from Dorset. These may have been dead enemy combatants, including mercenaries, who had been thrown into burial pits. The remains in Dorset largely included "British-like" DNA (35%) possibly from Scotland and/or Ireland, followed by "Norwegian-like" DNA (22%), "Danish-like" DNA (18%) and even "Italian-like" DNA(16%). The remains in Oxford were also of mixed ancestry and comprised "Danish-like" DNA (52%), "Italian-like" DNA (17%), Swedish-like" DNA (14%), "British-like" DNA (8%) and "Norwegian-like" DNA (6%). The percentages were derived from the Supplementary Tables S6 (Margaryan, see references below, 2020). The same study reports that the DNA evidence from Ireland implies a Norwegian origin for the remains of three Viking Age individuals found in Dublin and one found in Connemara.
The first two studies point strongly to the presence of people of Scandinavian descent in England before the Viking age. It would be interesting to know whether their language differed from that of their Saxon neighbours, if it did, that would increase the likelihood that they imported Scandinavian place names and language into England.
The research used a modern sample of 2039 people throughout the United Kingdom and a comparison group of 6,209 people from across Europe. It used "fineSTRUCTURE") to analyse the data. When mapped, clusters appeared of people with similar genetic composition. The study found that the present population of the United Kingdom formed 17 clusters of genetically similar individuals. The 6209 European people had their DNA examined in the same way. Again people with similar DNA were assigned to clusters (14 in all) as follows: two groups from modern western Germany, one from the Flemish part of Belgium, one from Denmark, four from Norway and two from Sweden, two from Germany, one from north-west France, one from southern France and Spain. The only Danish group that contributed to English DNA were from the North-West of Zealand ie near Coenhagen which is just 10 miles across the Oresund Bridge from Sweden. (There are no closely related groups in either Jutland or Angeln.) Again the Danish island of Zealand seems to be important in the story of the Germanic settlement of England. This Danish group was represented widely among English clusters including the cluster that covers most of lowland England. While much of England is genetically homogeneous, and includes both Danish and German genetic contributions, the situation north of the Tees is much more complex (see their Figure 1). It contains a variety of Scottish genetic sources. Rather surprisingly, the distribution of DNA Is reflected in the distribution of place names (see my Figure 4).
I particularly wanted to know whether there was evidence of substantial Viking Age tribal movements of Scandinavians into those areas where "by" place-name endings are prevelant. That would have been conclusive support for a Viking origin for those place names. Although the authors looked for such evidence, they did not find it. To quote, "... we see no clear genetic evidence of the Danish Viking occupation and control of a large part of England, either in separate UK clusters in that region, or in estimated ancestry profiles, ...". By contrast, they did find clear evidence of genetic differences in other places, for example, between Devon and Cornwall, North and South of the Tees, between North and South Wales, and elsewhere (see again their Figure 1). The people who brought the "by" place names must have done so so long ago tha they had blended into the rest of the population.
It is hard to know what to make of this. While "by" place names are concentrated in Lincolnshire, Leicestershire and Yorkshire, implying a Scandinavian presence in those places, there is no genetic trace. However there is a change in genetic markers to the North of the Tees where "by" place names cease and the genetic markers more closely resemble Scottish genotypes (see Leslie Figure 1). Could it be that British tribes held off the combined Scandinavian and Anglo-Saxon people long enough for them to merge genetically? Leslie et al might agree, since they make the point, "A critical observation which follows is that groups which contribute significantly to the ancestry profiles of all UK clusters most probably represent, at least in part, migration events into the UK that are relatively old, since their DNA had time to spread throughout the UK...". and again, "Ancestry shared with DEN18 could also have reached the UK in early migrations by land or sea, or in later migrations of the Danish Vikings. The fact that this group contributes some ancestry to all UK clusters is evidence that some of this ancestry sharing may indeed result from early migrations...".
Schiffels (2015, see references below) also published genetic research that year. They used a different technique, which focussed on the presence of relatively rare sequences of DNA. These were identified from a sample of modern Europeans. This enabled the researchers to construct a "tree" of European ancestry showing the occurrence of rare sequences within European lineages. They were also able to identify when those lineages diverged. The Dutch (taken as a proxy for Saxon) and Danish lineages separated more than 5,000 years ago. Ancient DNA samples from individuals buried at three sites in the east of England were compared with the European lineages. The sample size was small, consisting of only seven individuals with carbon 14 dates in the Anglo-Saxon period (the period that immediately predated the Viking age). Of three people in a group from Oakington, two had some Dutch ancestry and one had some Danish ancestry. Of three people in another group from Hinxton, a similar mix was found. The seventh person, also from Oakington, had a wider mix of ancestries including ancestry common to Finland, Cornwall, the Netherlands and Denmark.
To find out how many waves of immigrants had arrived since the Roman withdrawal they examined the length of strands of DNA in the individuals within their sample. It seems that DNA mixes somewhat like paint in a pot. Starting with two colours, paint would form strands when stirred. If we subsequently add a third colour and stir again, it would not be as well mixed as the first two. In this way we could see the sequence in which colours were added. In an analogous way, DNA mixes in strands or sequences of code. DNA from both parents is combined at conception, but it seems that some sequences can remain intact. The more frequently the population reproduces, the shorter those sequences become. Their length can be used as a guide to the number of generations after an "admixture event". A later addition to a mixed population should be identifiable by the longer DNA sequences associated with it. Assuming that the post Roman invaders mixed with the native Celtic population, that would have been a first "admixture event". If a significant Viking age immigration occurred subsequently and bred with the existing population, that would have been a second admixture. However, there was no evidence for this in mainland Britain. This led the authors to conclude, "… we see no clear genetic evidence of the Danish Viking occupation and control of a large part of England, either in separate UK clusters in that region or in the estimated ancestry profiles, suggesting a relatively limited input of DNA from the Danish Vikings ..."
The evidence in favour of a pre-Viking tribal migration of Scandinavian people into England is mounting. Myres found substantial amounts of pottery. Gretzinger et al found substantial amounts of ancient Scandinavian DNA in pre-Viking England. Leslie et al (see references below) used modern DNA and found no evidence for a second wave of mass immigration after the initial Anglo-Saxon conquest. I found that “by” names, so common in parts of England were largely absent from other north European settlements. So what is the evidence in favour of a Viking age origin for the extensive distribution of Scandinavian place names, and does it matter?
The evidence amounts to a couple of much quoted sentences in the Anglo-Saxon Chronicle. These tell us that elements of the Great Heathen Army, after spending 9 years rampaging around Britain, and presumably living off the land eventually settled down in East Anglia, Mercia, and Northumbria (where they grew their own food, presumably on the estates they had taken over). This is weak evidence for a mass Viking age immigration as authors like Sawyer (see references below), p209 have noted. It matters because the distribution of Scandinavian place names is taken as a proxy for Viking Age settlements. Perhaps less importantly it also matters because the Scandinavian influence on the English language is usually attributed to the Viking age conquests. If widespread pre-Viking Scandinavian settlement had occurred, then the re-integration of Northern and Western Germanic in the common speech of England could have been a much longer process.
Much of the information in this article has been reproduced in accordance with the requirements of the Creative Commons agreement, with acknowledgement to Gretzinger et al 2022
Gretzinger, J. et al., 2022.The Anglo-Saxon migration and the formation of the early English gene pool Nature Springer Nature. Retrieved 2023.
Kershaw, E. C. 2016. The People of the British Isles project. Antiquity, pp. 1670-1680.
Leslie, S., Winney, G. & Hellenthal, D., 2015. The Fine-Scale Genetic Structure of the British Population. Nature, pp. 309-314.
Margaryan, A., & al, e. (2020). Population Genomics of the Viking World. Nature , 390-396.
Sawyer, P. H., 1971. The Age of the Vikings. 2nd ed. London: Edward Arnold.
Schiffels, S. e. (2016). Iron Age and Anglo-Saxon Genomes from East England Reveal British Migration History. Retrieved from www.Nature.com.
Apple Down, Chichester, West Sussex
Dover Buckland, Dover, Kent
Widemouth Bay, Bude, Cornwall
Fox Holes Cave, Clapdale, North Yorkshire
Eastry Updown, Dover District, Kent
Ely, East Cambridgeshire, Cambridgeshire
Hartlepool, Olive Street, Unitary Authority Hartlepool
Dover Hill, Folkestone, Kent
Hatherdene Close, Cherry Hinton, Cambridgeshire
RAF Lakenheath, Eriswell parish, Suffolk
Lincoln Castle, Lincoln, Lincolnshire
Newquay, Crantock, Cornwall
Norton, Bishopsmill, Stockton on Tees
Norton, East Mill, Stockton on Tees
Oakington, South Cambridgeshire, Cambridgeshire
Polhill, Maidstone District, Kent
Rookery Hill, Bishopstone, East Sussex
Sedgeford, King's Lynn and West Norfolk, Norfolk
West Heslerton, Ryedale District, North Yorkshire
Wolverton, Radcliffe School Mid-Saxon Cemetery, Borough of Milton Keynes
Worth Matravers, Football Field, Dorset
Liebenau
Hiddesdorf
Dunum Lower Saxony
Issendorf
Drantum
Schortens
Zetel
Haeven
Lejre
Besser
Alken Enge
Trekroner
Barse
Hessum
Bodkergarden
Kumle
Gerdrup
Oland
kane
P95- p96. Northern Kent (probably first half of 5th century, similar to pottery found in Esbjerg (Western Jutland), Drensted (Western Jutland), Ribe (Western Jutland), Rubjerg (Northern Jutland).
P99. Yorkshire, Lincolnshire and East Anglia, first half 5th century, similar to pottery found in Danish Anglia as well as some Anglo-Frisian pottery.
P103. Deira and Lindsey, second half of fifth century, similar to pottery found in southern Scandinavia.
P111. Sussex, fifth century pottery with similarities to Norwegian pottery.