So there is no group that got their first and outfought the new immigrants who came later? None?
Basques, perhaps, and maybe the native Irish, Welsh and Scots. But that depends on definition of "native".
In fact, genetically speaking, majority of native populations of European countries are truly
native - as in, "we had been here since we came as Cromagnons and murdered Neandarthals" level of native.
But majority of them did not maintain their culture, because small groups of warrior-culture conquerors tend to have massive ability to overwrite local culture. English are still some 90% Celts genetically, but English language originates from Anglo-Saxon language, and culture is predominantly Germanic.
It is only in modern times that immigration could become massive enough to become an actual genocide.
The ultimate weakness of might makes right is that it opens you up to the same process being done on yourselves, and you might not always be the bigger fish.
Other ideologies also open you to "might makes right" however. It is just that your conquerors may decide not to opt for "might" if there are cheaper ways of screwing you into every orifice.