Even though this is black and white, she looks like a Flower Hmong. Surprising in Sa Pa, but wouldn't be so the east of Lao Cai. "Buing" - what is that? It is interesting to me that instead of pants, these tribeswomen use strips of fabric wound around the legs. My mother told me that her German grandmother (who grew up in Australia, did a similar thing, winding strips of fabric around her legs in the frosty Tasmanian winter, to keep warm. Funny how clothing ideas are so widespread across cultures!