Between 400 C.E. and 650 C.E., waves of Germanic invaders swept through the eastern United Kingdom. They conquered territory, set up regional governments, and mingled with a diverse local population that included indigenous British people and migrants from the far-flung reaches of the recently defunct Roman Empire. Modern British genomes are mostly a mix of these populations. But it has been difficult to determine just how much the invaders—Anglo-Saxons from Europe’s North Sea coast—contributed because of the small genetic differences among European groups. Now, researchers may have an answer. Using whole-genome sequencing, they looked at rare genetic variants in modern-day British populations and compared them with variants in the DNA of 10 ancient skeletons. The bodies, seven Anglo-Saxons and three preinvasion peoples, were buried near Cambridge, U.K., between about 100 B.C.E and 800 C.E. Writing in Nature Communications, the researchers report that 38% of the ancestors of people from the eastern United Kingdom were Anglo-Saxons. People from Scotland and Wales, meanwhile, have about 30% Anglo-Saxon ancestry. But if scientists really want to understand Anglo-Saxon genomes, they might be better off looking elsewhere in Europe. The researchers also determined that Anglo-Saxons were genetically similar to modern Danish and Dutch people.