Being L21 or somewhere downstream from that does not necessarily mean the British Isles, and to see that in haplotrees is pretty cool. While a lot of us look to the British Isles when we test somewhere downrange from L21, though labeled by Britain’s DNA as “Pretani”, it might be a little more complicated than that. As one commenter noted, perhaps it is better to consider it “Proto-Pretani/Brythonic”. I agree. In fact, I wonder if it might be considered Gaulish, though the mileage on that label may vary. In fact, even in some instances, if we moved downstream from L21 a tier or two, we still see these matches in places other than the British Isles (and I’m not including Scandinavian countries as that, when under L21, often means the interjection of Vikings in the British Isles).
In my own case, from the BY3368 haplotree, when I work back a short way to FGC3899 (BY3368 < BY3364 < L627 < CTS3655 < ZZ32 < FGC3899), I find my first encounter with some of these non-Briton lines…
As you can see, in the middle, there are two matches… one rooted in Spain, and the other in France (Torres and Loyen).
I initially thought this was indicative of the post-Roman occupation/Anglo-Saxon push migration of Britons…
Maybe it is, or… maybe it’s just the westward progression of Gaulish peoples into France and Spain. I sorta think it’s the former. Keep in mind, the last time these lines and my own shared a common ancestor was at the FGC3899 level, and according to the aging method developed by Iain McDonald, the median age of this block is 3439.57 YBP (1490 BC). The 95% confidence interval is 2013 BC to 1015 BC.
I have to go back a few more tiers before I encounter another anomaly with a match rooted in the Netherlands… and FGC9749 (which points to a test taker rooted in Belgium), and then BY9405 (Spain, again), and then a really interesting anomaly at BY178021… Germany. My guess is that the Belgium and German links in the haplotree are most definitely Gaulish. So, we get a glimpse of the migration of lines, as they relate to my Y.
Looking at my maternal grandfather’s line (Hillyard/Hilliard, NPE of the Nolan line of County Clare, Ireland… which is Type III Irish/Dalcassian/Dal gCais), the first break is more closely related on the haplotree, and rooted in Brazil… and considering Brazil was colonized by the Portuguese (and the surname is Deolindo), you have to wonder if the line is not specifically connected to Celtic story behind Évora. Using the aging method developed by Iain McDonald, the median age of the last shared ancestor of DC 55 and DC109 is in haplogroup Z17669, which has a median age of 1810 YBP (140 AD). The 95% confidence interval is 175 BC to 408 AD.
The next closest is a match claiming descent from an ancestor in Haiti… which likely means rooted further back in France.
Using my paternal mother’s father’s side… Nicholson (BY109515) of Cumbria/Cumberland, England, I don’t have to go back far at all before I encounter the first non-British Isles matches…
Of course, the countries represented here are Brazil, Portugal, and Ireland. The last time Y134034 and BY109515 shared a common ancestor was in haplogroup BY13693. Regretfully, BY13693 has not yet been dated by the McDonald method, but one tier above (BY25447) apparently emerged between 1989 BC and 804 BC.
So, if you test at the Big Y-700 level and look at the charts by Alex Williamson or the tables in FTDNA Y Groups like R L21, Z290 and Subclades, I think you’ll gain a better perspective on what you are seeing (if you haven’t done so already). It truly is amazing to put this side-by-side with the story of the migration of Celtic Brythonic (proto-Pretani/Brythonic?) people, especially those “closest” related to you.