"Most Holy Father and Lord, we know from the deeds of the ancients and we read from books -- because among the other great nations of course, our nation of Scots has been described in many publications -- that crossing from Greater Scythia, via the Tyrhennian Sea and the Pillars of Hercules, and living in Spain among the fiercest tribes for many years, it could be conquered by no one anywhere, no matter how barbarous the tribes. Afterwards, coming from there, one thousand two hundred years from the Israelite people's crossing of the Red Sea, to its home in the west, which it now holds, having first thrown out the Britons and completely destroyed the Picts, and even though it was often attacked by the Norse, the Danes and the English, it fought back with many victories and countless labours and it has held itself ever since, free from all slavery, as the historians of old testify. In their own kingdom, one hundred and thirteen kings have reigned of their own Blood Royal, without interruption by foreigners.“
So sayeth the Declaration of Arbroath, commissioned in 1320 by King Robert the Bruce of Scotland and signed by 39 Scottish nobles. It was sent to Pope John XXII as an argument for papal recognition of Scotland's independence following the defeat of an invading English army at Bannockburn in 1314, which followed almost two decades of English attempts to conquer Scotland. The narrative seems to be a contracted form of the story told in the Book of Invasions, an 11th century Irish text which offers the national origin myth of the Gaels, which included the Scots too.
A copy of the Declaration of Arbroath kept at Arbroath Abbey
The ultimate origin of the Gaels is traced back to Scythia (the steppes of Ukraine and Russia), while the Tyrrhenian Sea is the part of the Mediterranean Sea between mainland Italy and the neighboring islands: Corsica, Sardinia and Sicily. This route is rather peculiar and is not really backed up by the evidence that modern genetic science offers us. While the common origin of the Scots and Irish can now definitively be traced back to Scythia, the route they took seems to have been through Poland, Germany and the Netherlands; not through the Danube Basin, Italy and Spain. The genetic evidence also suggests that the ancestors of the Gaels migrated first to Britain and then Ireland, while the traditional story talks of a migration from Spain to Ireland to Scotland.
The question I wish to explore today then is if there is any evidence for an Iberian connection with the Gaels, since such an assumption even informed Spanish attitudes to the Irish in the late 16th century, as the Spanish and Irish were allied against the English who were attempting to conquer Ireland. The short answer is that there is overall very little evidence of a connection between the two, as the Scots and Irish cluster most with other peoples of the British Isles, followed by North-West Europeans more broadly (French, Belgians and Germanic people). So then, we may need to consider looking at possible specific instances of individuals migrating from Iberia to Ireland in prehistory.
As of this writing, there is no such evidence from the archaeogenetic record, which suggests all lineages in prehistoric Ireland represented with the genetic markers known as 'haplogroups' came from Britain. However, there are a small number of haplogroups known among modern day Irishmen that could potentially have come from Iberia (this sort of thing is easier to trace among men, sorry ladies); they are two haplogroups in particular: I2a-L160 and R1b-DF27.
The former could be found among Neolithic farmers of Sardinia, France and Iberia, though nowadays it's less common in France than the other two. While it seems most likely that L160 and all other I2a lineages would have arrived in Ireland from Britain (and before that, France via Normandy and Calais), it is possible that at least some came via the peculiar route from the Basque Country to Brittany and then to Britain and Ireland. This route is suggested by tracing the origins of a Neolithic pottery type called 'Beacharra ware' found in Scotland and Ireland1. Perhaps I2a-L160 hasn't been found among archaeological samples because the men that carried this lineage practiced cremation, so they've left no remains for us to analyze.
As with most other I2a lineages in the British Isles, they represent the remnants of the Neolithic farmers who were mostly replaced by the Beaker Folk in c.2500 BC, whose origins lay in Scythia and who provided the bulk of the gene pool of the modern-day Scots, Irish and Welsh. Most of the British and Irish Beaker folk carried R1b-L21, but it shares a common origin with DF27, which represents Beaker Folk who migrated mainly into Iberia (though it's also the most common R1b subclade in France today).
A 2021 study shows that at least some R1b-DF27 was ending up in Bronze Age England2, and while much of this was likely coming from France, some of the subclades show up more among modern-day Iberians. In the Late Bronze Age (c.1300-800 BC), the Atlantic was connected by a trade network that is referred to by archaeologists as the 'Atlantic Bronze Age'. It is within this context that Iberians could have made their way to the British Isles, as the archaeological evidence suggests that after 750 BC, communities in Scotland became more fragmented and less reliant on trade networks3, which would seem to have made long-distance travel less likely than before.
The distribution of R1b-DF27, which radiates out from Iberia
Around half of modern-day Irish DF27 samples show Iberian affinities, while one subclade in particular known as Y5058 is found among men with a pedigree of descent from King Breassal Breac of Leinster (c.500-200 BC) and analysis of the pedigrees of men with different surnames strongly suggests this was the original lineage4. This clearly shows at least one DF27 lineage had made its way to Ireland by the Iron Age, while the closest relatives of this subclade are today found in Iberia. A number of modern-day Scotsmen also carry DF27 subclades with Iberian affinities (though they tend to be different from the Irish ones), so this could also reflect Bronze Age immigration; though no DF27 as yet has shown up in the Scottish archaeogenetic record either.
If there was Iberian immigration to Ireland or Scotland, it must have been very small and indeed the DF27 that does appear in Bronze and Iron Age England is heavily outnumbered by L21 and other British or French/Belgian haplogroups. The 2021 study found no evidence of increased Neolithic farmer admixture in Scotland compared to England and Wales, which makes it look like any Iberian immigration to Scotland in the Bronze Age would have been tiny or non-existent (though the study unfortunately didn't cover Ireland).
It's therefore not clear at all why the Gaels traced their origins to Iberia, since the only way this would work in the context of the genetic evidence would be that, for some reason, they adopted the origin story of a very small number of potential Bronze Age Iberian immigrants for themselves; even though the genetic evidence clearly shows the bulk of Irish genes came via Britain. Also, DF27 itself would not have arrived in Iberia via the Tyrrhenian Sea as in the traditional tale, but from France.
At the very least, this shows that the medieval Gaels at least thought of themselves as more akin to the Iberians than their British neighbors, the reasons for which are lost to the mists of time. Perhaps in the open and interconnected world of the Atlantic Bronze Age, influential individuals made a long journey from a homeland in Iberia and eventually ended up in Ireland. Perhaps they were missionaries for some new religion that cannot be known for lack of texts, or perhaps their stories of a dry and sunny land sounded appealing to the Bronze Age Irish who at times resented the cold, wet climate of their own country.
However this tale came about, I should still say it indicates that despite their overall genetic similarity with other North-West Europeans, the Scots and Irish (and the Welsh, for that matter) do seem to have more of an affinity to Southern Europe compared to other Northern Europeans, and I would suggest this is most likely to do with the Atlantic Bronze Age. Additionally, it could also could have something to do with the Neolithic farmers already present in Scotland and Ireland; for instance, modern Scots and Irish are genetically closer to a Neolithic Irishwoman ('Ballynahatty Woman') than the English or Welsh are.
Ballynahatty Woman had the closest genetic relation to modern-day Sardinians, but Iberians also share a close connection too, while the Scots and Irish have only marginally more that other Brits
As a last note on the subject, my analysis of Scottish R1b-L21 suggests that, contrary to the story in the Declaration of Arbroath, there was no mass Irish immigration (at least not into Northern Scotland) and so the Gaelicization of Northern Scotland was cultural and probably driven by a small number of men represented by some L21 lineages (mainly M222 and perhaps some others too). So even if there was Bronze Age Iberian migration to Ireland, this matters less for the medieval Scots, of whom only a minority seem to have been descended from Irish immigrants anyway.
Conor Cummings
1Piggott, 1954: Neolithic Cultures of the British Isles, p.170
2https://www.academia.edu/66040460/N_Pattrson_et_al_2021_Large_scale_migration_into_Britain_during_the_Middle_to_Late_Bronze_Age
3Armit, 2016: Celtic Scotland, p.99