Fascinating trying to find the way through history, and what was real versus legend. I remember seeing another older source writing about importing to the US, if I remember correctly, and how much variation there was in the original birds in China. I can see the possibility of some selected breeding from a Buddhist monastery developing a gentle beautiful bird like what is described in the literature, and as you say, eventually using the Langshan descriptor for all the regional birds and losing the original stock in favor of traits more apt to survive outside of a sheltered environment?