Furthermore , some proto - Celtic was spoken over all of Greater Britain , and this particular spelling is prototypical of those more populous regions .
Rather , Pytheas brought back the P - Celtic form from more geographically accessible regions where Welsh or Breton are spoken today .
Some proto - Celtic was spoken over all of Greater Britain , and this particular spelling is prototypical of those more populous regions .
Rather , Pytheas brought back the P - Celtic form from more geographically accessible regions where Welsh or Breton are spoken today .