My mother bought the embroidered pants below at the Chiang Mai night market in Thailand in the mid eighties. They’re from the Yao (or Mien) Hill Tribe.
My mother was told by a Thai friend of hers that traditionally the women in the tribe embroider one pair of these pants per year. They change to the new pants at the hilltribe’s New Year celebration (not the calendar new year) because it’s bad luck to wear old clothes in the new year.
I’m not sure how accurate this story is, since a year is a long time to wear the same pants.
Looking closely, much of the embroidery is cross-stitch. Some of it seems related to needlepoint, and there are also a few bands of work that seem like they may be a relative of blackwork. The designs are very geometric, and the color scheme for the pants is different from a standard western palette.
Here’s another photo of hilltribe women in traditional clothes.