While we were in Yunnan, the tour guide talked a lot about the local lifestyles. It was pretty amazing. We were even invited to a local dance where, apparently, the ladies will sometimes choose a foreigner to go home with her. We saw some local children playing that were obviously of mixed race.
Also, my wife was telling me that 3 local men in her village had married Vietnamese women. Language is an issue, but immigration is easy. Unfortunately, all 3 women scammed their husbands and disappeared in the night with their money.