“The purpose of propaganda is not to persuade or convince, but to humiliate.”1
We have been taught that the ancestors of the Gaels were Milesians from Iberia who invaded Ireland circa 300 BC bringing the Gaelic language to the island.2,23 We have also been taught the Irish Gaels invaded Scotland after the Romans abandoned Britain thus bringing Gaelic language to Scotland.3,4 Yet, if one pauses to analyze these invasions in depth, they seem beyond belief. Beyond belief does not make them untrue per se. If there was strong corroborating evidence such as archaeological findings of major battles, linguistic evidence of pidginization of Gaelic language, genetic evidence of concurrent mass migration, etc., we would feel more confident in believing what seems, at first analysis, unbelievable.
In truth, we do not have archaeological findings of major battles.20 Belittling nomenclature (e.g., Primitive Irish) notwithstanding, we do not have linguistic evidence of pidginization of Gaelic language or of any Celtic language.5,22,24 We do not have genetic evidence of Iron Age mass migration from Iberia to Ireland or of Medieval migration from Ireland to Scotland. Instead, we have genetic evidence of Britain and Ireland largely being populated by an Indo-European mass migration circa 2500 BCE.6 That 2500 BCE migration brought descendants of a man bearing the R-L21 Y haplogroup to Britain and Ireland. Those migrants are the ancestors of most Irish and a plurality of Scottish men today.7,8 We have genetic evidence of Britain later receiving another wave of mass migration of Indo-Europeans, during the Bronze Age, but this second migration, closely genetically related to the earlier migration, stalled in Britain.9 We have archaeological evidence of brisk trade between Southern Britain and the Continent, circa 1800 BCE, but scant trade between Southern Britain and Northern Britain at that time.10 We have linguistic evidence that Gaelic language was not pidginized.11
We also have heretofore not well explained phenomena related to the Gaels. What caused the Romans to build walls instead of declaring victory over the Scots? What created the Gallowglass? What created the Borderlands/Scots-Irish penchant for military service?27
Regarding the Roman walls, we are told, they were built to contain the Picts. There has been much quibbling about just who or what Picts were, but academics now believe they were a Brythonic speaking group. Archaeogenetic results support the Picts as having descended from the R-L21 Indo-European migration of 2500 BCE.12,13 This certainly makes sense. Southern Britain was known to be Brythonic speaking by the Romans. Many Scottish place names appear to be of Brythonic origin. (I believe) early Gaelic speaking Christian missionaries needed translators to proselytize to the Picts. Yet, there are significant questions that are not explained by Picts simply being Brythonic speakers. If they were simply just another Brythonic speaking tribe, wouldn't they have succumbed to the Romans just like every other Brythonic speaking tribe? Of course, it's certainly possible that the Picts were just a little different from their southern cousins, but it is still something to consider. More significantly, how (and why) could Pictish Scotland become Gaelic speaking after the Romans abandoned Britain? We are told Irish invaders brought Gaelic to Scotland. Another pause, to consider this invasion, tells us it was extremely unlikely to have occurred. The Picts were not dominated by the Romans and, we have no evidence that they became a Classical Latin speaking population. To believe an invasion of the Picts by Irish Gaels occurred, we have to believe that Irish Gaels did what the Romans could not do: Dominate the Picts and force them to speak a language laden with complex verb systems, initial consonant mutations, intricate conjugations, etc. So, what explains the Picts? We can use a historical analogue in how Scotland became Anglophone. Picts were likely a Brythonic speaking elite from Southern Britain ruling over Gaelic speaking commoners in Northern Britain. When the Pictish elites lost power to the Gaels (thus ending the historical analogue), Scotland lost its Brythonic speaking population. So, we can imagine the Picts as primarily Gaels, Gaels who had spent the previous two millennia defending themselves from Brythonic encroachment from the Continent and Southern Britain. That explains how the people of Northern Britain were well prepared to defend their border when the Romans arrived in Britain.14
The Gallowglass, we are told, are Norse-Gaels. Yet, the quintessential Gallowglass, the Sweeneys, are clearly R-L21 Gaels descended from the Indo-European migration to Britain circa 2500 BCE. The Sweeneys are also descended from the same source population that produced the storied Picts. The Sweeneys are descended from Medieval migrants who relocated to Ireland from Scotland.15 We can see these relationships in their Y DNA.16,25 The other families for whom we have evidence of being Gallowglass, the Sheehys and some O'Donnells, are cousins to the Sweeneys sharing a common paternal line ancestor with them circa the 6th century CE. The Sheehys and those O'Donnells are also descended from men who migrated from Scotland to Ireland during the Middle Ages.17,18,29
To explain the Borderlands/Scots-Irish penchant for military service, consider that they are descended from people who withstood the Romans for hundreds of years, produced the Gallowglass, and likely resisted Brythonic encroachment from the South for more than a millennium before the Romans reached Britain.
The more recent conjecture related to Gaelic history, "Celtic from the West", assumes Celtic language to have been a lingua franca.21 A glance at Old Irish should disabuse anyone of gladly accepting that conjecture.26 Well attested Celtic languages are laden with complexities of grammar and pronunciation that make the likelihood of them having been lingua franca extremely unlikely.24 Anyone unschooled in Celtic languages can study Irish (Gaelic), Scottish Gaelic, and Welsh on duolingo.com. You can make quick comparisons of the languages using Google translate on fundamental concepts common to all Indo-Europeans (e.g., use translate.google.com on this phrase, "My cow does be eating grass and drinking water."). You will learn two significant things: 1. Brythonic and Gaelic languages are very different from each other. 2. Brythonic and Gaelic languages are very challenging for a non-native speaker to learn. Unsurprisingly, anywhere Celtic language has spread during the historical era (Cornish to Brittany, Irish to Boston, Scottish Gaelic to Cape Breton, Welsh to Patagonia) the language has only been passed on to the children of native speakers (if passed on at all). Any theory or conjecture that relies on Celtic language spreading via "cultural diffusion" ipse dixit cannot be easily accepted. It needs solid evidence, for us to consider it. Ipse dixit is not solid evidence.
Note that the highlighted terms above show a pattern of the Anglosphere belittling Gaels in defiance of evidence: "Gaelic language is primitive," "The Picts, not Gaels, withstood the Romans," and "The Gallowglass were first Norse, secondarily Gaels." This belittling is propaganda. Calling Gaelic language primitive is propaganda. The uncritical academic acceptance of the ridiculous Gaelic invasion stories is more propaganda. Uncritical academic acceptance of "linguistic diffusion" tales, framing Gaelic language as if it were a lightweight patois that could just blow-in to Ireland and Scotland, is propaganda. Finally, the DNA of the Picts and the Gallowglass show us they were more Gaels than they were anyone or anything else. It's just more propaganda to posit that the Picts and Gallowglass were not primarily Gaels.
Anti-Gaelic propaganda has been quite effective in marginalizing the Gaels and their language to the degree that many Gaels have given up. They have fled their ancestral homelands. Gaelic language has gone from being widely spoken as a community language in the 19th century to a language that is rarely heard outside of festivals, academia, and certain Gaelic media.19 The Gael has stopped speaking his own language...to his own family...in his own home...in his own country.
The opposite of propaganda is science. We have evidence in linguistics, archaeology, and DNA that lead us to a theory that well explains phenomena related to Gaels without humiliating our audience. The Gaels and their language are not blow-ins to the "British Isles."28 The Gaels, and their language, are the descendants of the first Indo-European mass migration to Britain and Ireland circa 2500 BCE.