"so it (West Wales) retained a lot of its autonomy in exchange for peace and trade" More details here .

 See this link

See this link

  Green for Devon, Black for Cornwall, the Somerset Dragon and Yellow for Dorset (should they be incorporated into the devolved nation of West Wales (The Western Welsh (The Western British)). 

Devon, Cornwall and Somerset, the ancient lands of West Wales (Dumnonia) are as unique in Britain as it’s Celtic cousins in Wales, Scotland and Ireland. However it lacks the authority enjoyed in those lands to address its own causes and concerns.