Hello Y_____, I see you are still pushing that "wave theory" despite the complete absence of a source population.
For the rest of you, here is the story of I2a2b:
Our Pre-Isles people were living in Doggerland until the tsunamis and sea level rise submerged the land at 6,200 BC. They migrated toward an area now underwater off East Anglia. There our Isles B founder was born about 6,000 BC. These were a mesolithic hunter/gatherer people living a precarious existence. But they did survive and the sea level did continue to rise driving them to the west. The Pre-Isles group may not have been so lucky, as the number of their descendants seems very small. More about that presently.
About 4,000 BC the founder of C1 was born, whether to a B1 parent or to a Pre-Isles parent is not clear. The C1 became a relatively prolific branch. This was about the time that neolithic practices took hold, so that may account for their success. It may also be because they had slightly different circumstances.
The first neolithic farmers to arrive in southern Ireland seem to have been using seeds adapted to the climate of Spain. These did not do well in Ireland and the resulting crop failures may have caused a regression to mesolithic status for those folks. When the crop fails, you eat the cow, and you are back to hunter/gatherer. The archaeological facts correspond astonishingly well to the legend of Parthelon who arrived in boats from the south bringing oxen and plough, but whose efforts failed in a fairly short time.
The farmers of northern Europe were using crops that were much more hardy in colder climates. When these seeds reached northern Ireland, perhaps carried by the hands of the C1, the neolithic revolution really took off. The map in the link below shows the success of the neolithic people mostly in the north.
Perhaps 3,500 BC, some C1 arrived in the north of Ireland where their successful ways continued, based perhaps on having the right seed stock. They were a minority population but they may have built up locally strong tribal groups and positions - like Rathcroghan. As time went on, their culture may have evolved and merged into the Cruthin. [The legend of Nemed does not seem to fit with what we hypothesize about the C1 and the Fir Bolg were very much too recent to fit either, so the legends seem to have skipped the Isles-C.]
In Ireland, C2, D1, and D2 were founded and spread.
Back over in southeast England, about 2,800 BC the founder of A1 was born (again whether to a B1 parent or to a Pre-Isles parent is not clear, but I would bet on Pre-Isles.) followed shortly by A2. The A1 seem to have moved west across southern England and on to Cork, where their main population seems to remain. The time and location correspond very well with the production of copper in Cork and trading in copper across England to the continent.
The A2 spread northwards and are found in England and across into northern Ireland.
All of these were in Ireland and Britain a very long time, thousands of years, before any of the more famous invaders - Celtic, Iberian, AngloSaxon, Fir Bolg, Milesian, etc, etc.. - arrived.
But they were not the first.
The modern population of Isles-B seems to be disproportionately small and Pre-Isles is nearly extinct.
There is a speculation that would account for that: we must remember that they were living in East Anglia. When the famous invaders - the Angles, Saxons, Jutes, etc, etc. - began arriving, East Anglia is where the invasions began and the invaders just kept coming. The locals were subjected to centuries of continuous warfare that resulted in a massive ethnic cleansing called the "Dark Horror". As much as 85% of the male population were killed and the women taken as wives for the invaders. A few surviving male children were shipped or traded back to the continent as captives where their descendants are still found in very small numbers as erratic occurrences of Isles B1.
(Cheerful corrections cheerfully welcomed)
Here is a nice summary of the history:
http://www.doveslightcoven.0catch.com/March/mesoneolithic.htm
Here is a map that shows the whole journey:
http://danel.us/resources/Grandfathers+Path9.pdf
And another that shows the events since Doggerland:
http://danel.us/resources/Doggerland+Isles+B.gif
And if you want to do your own subclade work:
http://danel.us/resources/Subclade+Predictor+TMRCA+ancestry+format+v5.xls
I would ask all of you I2a+ folks to do two things:
1) post your results on ysearch.org and
2) join ancestry.com i2a2b group (it's free) and also post your results there.