A county of England, Brythonic Welsh in origin, but more or less culturally assimilated save in a few regards, much more so than Wales. Population around half a million. Cornwall is known for its tin mines, which originally drew the Romans to Britain (so we can blame the Cornish for all that), and also for the invention of the Cornish Pasty, designed as a portable lunch for the tin miners. Modern Cornwall is also known for its submarine base and nutcase surfers, as well as the city of Newquay (pronounced Nyookie, or Nookie in American English) which draws thousands of optimistic American tourists every year.
Those Americans that have not been taken in by this and actually visited Cornwall tend to believe that it is still some sort of virulently Celtic superpower that takes up all of Devon, Somerset, Hampshire and indeed all of old Wessex, if not the entire island of Great Britain. The Empire of Great Cornwall can be found on many maps in the Map Thread and never fails to drive several English members, notably Thande, into a frothing rage.
The Cornish language, Kernow, died out some time ago but there have been some attempts at a revival.