http://www.familytreedna.com/groups/r1b-df27/about/background
BigY R-DF27 Project

https://en.wikipedia.org/wiki/Haplogroup_R-DF27
In human genetics, Haplogroup R-DF27 (R1b1a2a1a2a) is a Y-chromosome haplogroup which is a subdivision of haplogroup R-M269 (more specifically, its subclade R-) defined by the presence of the marker DF27 (also known as S250). Along with R-U152 and R-L21, the lineage is to a significant extent associated with Proto-Celtic, Celtic and later Celtiberian movements.

It arose comparatively recently, after the beginning of the European Bronze Age, and is mostly prevalent in the population of the Pyrenees region. The regions where it has been mostly found are Basque Country, Navarre, Asturias, Galicia, Portugal, Aragon, Catalonia, Pyrénées-Atlantiques as well as some presence in Great Britain and Ireland, though it has been found in smaller quantities as far away as Germany and Poland.

Specific subclades of DF27 have been associated with specific groups of people, for example R-M167 is associated with the Catalans and R-M153 is associated with the Basques.[1]