There have been some studies on the DNA of various populations; one problem with using DNA as a marker is that the easy one to trace is mitochondrial DNA, which is inherited solely from the mother; thus where a bunch of murdering rapists arrive, kill the men and rape the women, as may have happened more than once in British history, with the Saxons and then the Vikings, they leave no trace on the mitochondrial DNA.
One interesting bit of research concerns Madagascar; the island was settled not by Africans but by Malayo-Polynesians, it seems that one ship, quite possibly carrying an export cargo of female slaves, drifted across the Indian Ocean and made Madagascar; the exact number of women on the ship can be established from mitochondrial DNA.
On the basis of linguistic markers, Jared Diamond suggests that all the Malayo-Polynesians, from Easter Island to Madagascar via Java Malaysia and the Philippines, originated from Taiwan, via the Philippines.
