Well, the Mabinogion or Mabinogi aren't a people. The Mabiniogion are the most famous Welsh Celtic stories, dating back several hundred years.
If the question is actually "Are the Welsh the same as Britons" then the people who became Welsh (the Celts) were probably the original Britons.
The Britons was created in 1919.
As of July 2011, one poll estimates that 43% of Britons feel the laws should be changed to permit same-sex couples to marry in the United Kingdom. In another poll, conducted in June 2009 61% of the Britons agreed with the statement 'Gay couples should have an equal right to get married, not just to have civil partnerships.'
Philippines was not conquered by Britons anytime.
Arthur of the Britons was created in 1972.
Arthur of the Britons ended in 1973.
230,000 britons british were killed
The Britons and the Gauls did have something in common--their language.
Britons Publishing Society was created in 1923.
Young Britons' Foundation was created in 2003.
5000 Germans and 200 britons
i do not really know, but i don't think they have anything in common
It means "tattooed"! The immediate meaning of "Brittnee" is "woman of the Britons". The Britons were the ancient inhabitants of Britain. Outsiders called them "Britons" - "tattooed people" - because they painted themselves blue with woad.