There is genetic evidence of people from the Balkans migrating to Wales during the Roman era: https://academic.oup.com/mbe/article-lookup/doi/10.1093/molbev/msm

There is genetic evidence of people from the Balkans migrating to Wales during the Roman era: https://academic.oup.com/mbe/article-lookup/doi/10.1093/molbev/msm049 https://academic.oup.com/mbe/article-lookup/doi/10.1093/molb...