The undifferentiated subclade of Haplogroup I2a is centered in the Balkans,
where its founders may have taken refuge from the Ice Age. After the Ice Age, I2a spread into
Eastern Europe. Unlike subclade I1, it is not commonly found in Scandinavia and Western Europe.
Where it is found in Britain at all, it may reflect the genetic influence of Roman troops and settlers,
many of whom came from the Balkans or other parts of southeastern Europe.
Another subclade, formerly known as I2b2, may have originated in Sardinia and spread into Iberia
and France, after migrating to the British Isles during the upper Paleolithic. A recent study has indicated
that this subclade, although far more common in Sardinia than anywhere else, also occurs among the Basques,
and in Ireland at a rate of about 2.6 percent. Since this subclade is found among the Basques and the Irish,
one may assume that it was part of the genetic make-up of the aboriginal population of Western
Europe - a kind of junior partner to the much more widely prevalent AMH.