into the Iberian peninsula or prior population movements and whether Haplogroup L is linked to the slave trade or prior population movements linked to Islamic expansion. A majority of Haplogroup L lineages in Iberia being North African in origin points to the latter. In 2015, Hernández et al. concluded that "the estimated entrance of the North African U6 lineages into Iberia at 10 ky correlates well with other L African clades, indicating that some U6 and L lineages moved together from Africa to Iberia in the Early Holocene while a majority were introduced during historic times." Haplogroups Y-Chromosome haplogroups Like other Western Europeans, among Spaniards and Portuguese the Y-DNA Haplogroup R1b is the most frequent, occurring at over 70% throughout most of Spain. R1b is particularly dominant in the Basque Country and Catalonia, occurring at rate of over 80%. In Iberia, most men with R1b belong to the subclade R-P312 (R1b1a1a2a1a2; as of 2017). The distribution of haplogroups other than R1b varies widely from one region to another. In Portugal as a whole the R1b haplogroups rate 70%, with some areas in the Northwest regions reaching over 90%. Although R1b prevails in much of Western Europe, a key difference is found in the prevalence in Iberia of R-DF27 (R1b1a1a2a1a2a). This subclade is found in over 60% of the male population in the Basque Country and 40-48% in Madrid, Alicante, Barcelona, Cantabria, Andalucia, Asturias and Galicia. R-DF27 constitutes much more than the half of the total R1b in the Iberian Peninsula. Subsequent in-migration by members of other haplogroups and subclades of R1b did not affect its overall prevalence, although this falls to only two thirds of the total R1b in Valencia and the coast more generally. R-DF27 is also a significant subclade of R1b in parts of France and Britain. R-S28/R-U152 (R1b1a1a2a1a2b) is the prevailing subclade of R1b in Northern Italy, Switzerland and parts of France, but it represents less than 5.0% of the male population in Iberia. Ancient samples from the central European Bell Beaker culture, Hallstatt culture and Tumulus culture belonged to this subclade. R-S28/R-U152 is slightly significant in Seville, Barcelona, Portugal and Basque Country at 10-20% of the total population, but it is represented at frequencies of only 3.0% in Cantabria and Santander, 2.0% in Castille and Leon, 6% in Valencia, and under 1% in Andalusia. Sephardic Jews I1 0% I2*/I2a 1% I2 0% Haplogroup R1a 5% R1b