I ALWAYS thought a Black Country person, and especially a yam yam, was someone defined by human characteristics not so much borders.
It was the industry and tough conditions that helped create those characteristics, such as hardworking and self reliant, getting on with things, down to earth, strong hands and a warm heart, nice and friendly but equally direct and no nonsense.
They have a hatred of rules and a fierce sense of independence in thinking. They are a quick talker and direct in speech, but not rude (ok at times it can appear like that).
I always thought that yam yams especially have a dry, witty sense of humour. I know my family never take anything that serious, always like a joke, a good time (work hard and play hard) where money and possessions aren't such obsessions but may appear downtrodden at times (realistic).
Add to that shared language, industrial heritage, working class roots, love of working clubs and pubs (drinking ale), such characteristics are not always easy to define. I do find people outside can be solemn and a little too serious.