 Maternal gene flow to Europe from sub-Saharan Africa began as early as 11,000 years BP, although the majority of lineages, approximately 65%, are estimated to have arrived more recently, including during the Romanization period, the Arab conquests of southern Europe, and during the Atlantic slave trade.A 2007 study by Bauchet, which utilised about 10,000 autosomal DNA SNPs arrived at similar results.Principal component analysis clearly identified four widely dispersed groupings, corresponding to Africa, Europe, Central Asia and South Asia.