I think the people we meet in dreams we may not recognize their physical features but "who" they represent is someone we know. Our dreams are made up out of our own head; we can't really come up with a "stranger". Even the physical features we have put together from those who we have seen/know in some way. True, I'm not going to "know" a man from China but what "China" means to me, who/what the person represents will be known to me, will not be a "stranger" unless I allow it to be a stranger for my purposes. The stranger cannot get himself into my dream, I have to let him in and I do that with intent, if only unconscious intent.