The Picts

[MOESAN]

I may have misunderstood. I see "Celtic" culture as being an Iron Age phenomenon. Certainly, there were antecedents (Urnfield < Tumulus). I think it was a relatively sudden change, rather than a gradual one, brought about by an incoming technologically advanced (iron-using) culture ("people", not just "pots"). Without iron, I don't think they would otherwise have made the headway they did into the "Pretanic Isles" - there may have been incursions, between the Bell Beakers and the Celts, but they likely were absorbed and didn't leave much of a trace. The people who were already there (Bell Beakers, etc.) weren't an entirely alien culture (being Indo-European) and weren't replaced or wiped out, so there was likely some "blending".

I think the so-called "Cruithni" were likely Brythons who migrated to Ulster from Scotland (Ayrshire and Galloway?) before the formation of surnames (thus, with "Irish" surnames), likely containing both I2a and R1b lineages. Later inputs into Ireland would have been from Vikings, Anglo-Normans, Galloglasses, Protestant Plantationers, Highland/Border Clearances, Scottish Regiments, etc., also containing both I2a and R1b lineages.

The difference with the I-M284..L1195..L126+ line is that it goes back to the Neolithic, and possibly the Mesolithic, in Britain (England, Wales, Scotland, and Ireland) rather than coming in with later groups.

I suspect that the Irish Sea, at least in the late-Bronze/early-Iron Ages, was more of a genetic/linguistic barrier than a "marine highway" - wide-spread seafaring, and piracy, under sail, was likely a later development.

I agree with the most of what you say here.
Just, for me Celts took foot in the Isles through South (not an overwhelming move but some tribes) before IA La Tène -
Concerning Y-I2a, some of them could have been in the Isles at Mesolithic, but the most I think (and so perhaps other Y-I2a, came during middle to late Neolithic with the famous old termed "Long Barrows", maybe with solid ties with continental megalithic people (this people had some influence until Scandinavia) - This don't exclude other clades of Y-I2a coming with Germanic more or less numerous groups after beginning our era, maybe even before. - all that 'd deserve a precise study of the divers subclades of Y-I2a, work I have'nt the courage to do myself! -

 

[CrazyDonkey]

I agree with the most of what you say here.
Just, for me Celts took foot in the Isles through South (not an overwhelming move but some tribes) before IA La Tène -
Concerning Y-I2a, some of them could have been in the Isles at Mesolithic, but the most I think (and so perhaps other Y-I2a, came during middle to late Neolithic with the famous old termed "Long Barrows", maybe with solid ties with continental megalithic people (this people had some influence until Scandinavia) - This don't exclude other clades of Y-I2a coming with Germanic more or less numerous groups after beginning our era, maybe even before. - all that 'd deserve a precise study of the divers subclades of Y-I2a, work I have'nt the courage to do myself! -

We know that I-M284 samples were interred in New Grange c.5700 ybp, representing a ruling-elite, and possibly god-king status, since one was determined to be the result of first-degree incest. (New Grange is the penultimate "long barrow".) While M284 has only been found in Ireland (and, downstream, L1195 in Ireland and Britain), we don't know if it originated there or on the Continent. I-CTS616, two steps up, has been found in Germany (Falkenstein, c.9161 ybp), Ukraine (Volniensky, c.7313 ybp), Germany (Weltzin/Battle of Tolense, c. 3200 ybp). For a distribution of CTS616+. see:

https://haplotree.info/maps/ancient...DNA_Y_Haplotree&searchfor=CTS616&ybp=500000,0

Long Barrows are a hallmark of the overall Neolithic "Megalithic" Culture in NW Europe. Where or when the "admixture event" occurred that temporarily put I-M284 on top of the "status" ladder is unknown.