<P> This number is confirmed by the archaeological evidence . The excavations at Spong Hill, for example, revealed over 2,000 cremations and inhumations in what is a very large early cemetery . However, when the period of use is taken into account (over 200 years) and its size, it is presumed to be a major cemetery for the entire area and not just one village, it does point to a smaller rather than large number of original immigrants of 20,000 . </P> <P> Heinrich Härke concluded that "most of the biological and cultural evidence points to a minority immigration on the scale of 10 to 20% of the native population . The immigration itself was not a single' invasion', but rather a series of intrusions and immigrations over a considerable period, differing from region to region, and changing over time even within regions . The total immigrant population may have numbered somewhere between 100,000 and 200,000 over about a century, but the geographical variations in numbers, and in social and ethnic composition, should have led to a variety of settlement processes ." </P> <P> Generally, the problems associated with seeking estimates for the population before AD 1089 were set out by Mark Thomas, Michael Stumpf and Heinrich Härke . They suggest that "Incidental reports of numbers of immigrants are notoriously unreliable, and absolute numbers of immigrants before the Norman period can only be calculated as a proportion of the estimated overall population ." </P> <P> However, there is a discrepancy between, on the one hand, archaeological and some historical ideas about the scale of the Anglo - Saxon immigration, and on the other, estimates of the genetic contribution of the Anglo - Saxon immigrants to the modern English gene pool (see "Molecular evidence" above). Mark Thomas, Michael Stumpf and Heinrich Härke created a statistical study of the two groups: those who held the "Migrant" Y chromosome and those that didn't . They examined the effect of differential reproductive success between those groups, coupled with limited intermarriage between the groups, on the spread of the genetic variant to discover whether the levels of migration needed to meet a 50% contribution to the modern gene pool . What they found is the genetic pool can rise from less than 5% to more than 50% in as little as 200 years with the addition of a slight increase in reproduction advantage of 1.8 (meaning a ratio 51.8 to 50) and restricting the amount of female (migrant genes) and male (indigenous genes) inter-breeding to at most 10% . </P>

In which order were the following countries invaded by britain