tsubaki
Player Valuation: £90m
Normans replaced mostly aristocracy, no? Ordinary people remained (culturally) Anglo-Saxons and Germanic language prevailed over Franco-Norman (who of course added their own influence).
Same way with Franks in what would become France, Germanic tribe of Franks invaded Roman (very populous) Gallic provinces and replaced their ruling structure. But they were too few in numbers and with centuries simply got swallowed in Romanized Gallic populace, only name of the country remained.
Or take Spain for example, nothing remains of former Germanic Visigothic Kingdom.
The language thing is especially important given what happened at the start of the Dark Ages, when Saxon rule was established in what is now England - modern English contains very few words from old Welsh except place names, which would suggest something approaching a genocide occurred.