Yes, if the implication was about "pure" populations, i agree with that completely. What i find most interesting is the extent to which (it appears) that the old resident populations were not much affected by the invasive groups. A lot of that is understandable. The Danes, for example, for most of a century, controlled half of what we would call England, and for a generation, controlled all of it. But in both cases, they did not even rise to the dignity of 10% of the population, and they needed the old base population reasonably content and productive. We don't know for earlier groups, but that was probably always the pattern--a conquering group did not exterminate the people they conquered, and needed at least their acquiescence in the new dispensation. Happy peasants, perhaps not, but at least contented peasants if they wanted the system to work; they needed their labor to generate wealth.