[geb]

The Welsh have an old saying that their land rightfully belongs to them and commonly refer to England as Lloegyr or "the Lost lands".
On what grounds to they claim the land to be theirs? Is it because they were allegely the first to arrive there (a few centuries before), or is their a deeper reason?

Land dispute and revendication are not uncommon conundrums nowadays...

i've always wandered what makes certain groups/nations feel they have more of a right to landship than others.

[Decky]

The Welsh have an old saying that their land rightfully belongs to them and commonly refer to England as Lloegyr or "the Lost lands".
On what grounds to they claim the land to be theirs?

It was theirs (you can tell from the pre Anglo-Saxon place names) but then the Angles the Saxons and the Jutes came the people who had lived on the land before were pushed out to Wales, the highlands of Scotland and Cornwall.

[Otebo]

The population displacement/extermination myth has been thoroughly disproven, Decky. Nobody was pushed out. The English are largely of the same stock as the Welsh and Scottish.

[geb]

Does the fact that they depict the English as foreigners, even on English soil, mean that they consider to have an inborn natural right to these "lost lands"?

[Rich]

Well the Welsh certainly lost some land to the English. They lost it culturally. I strongly suspect they lost it Y Chromosome wise ie the Paternal lines. They definitely didn't lose it in terms of mitochondrial DNA ie the Maternal lines. To what degree they lost it genetically ie in terms of the main 43 Chromosomes I'm not exactly sure. Perhaps the key question is whether they ever lost the East of England in any sense at all. East Anglia was never Welsh. The idea that a few hordes of Angles, Saxons and Jutes transformed us in a century or two from Celts to Germanics is preposterous. It would be like expecting the few Roman legions that occupied us for over four hundred year to have turned us into Latinos. Its preposterous.