Thanks Susan for your very informative comments!
So that means the skirt I posted was the wrong way up, and what I had labelled the "waistband" was actually the hem. I've re-posted it below the right way up...

The motifs are very similar to the ones on one of your two skirts
I have not seen many of these skirts with Chinese traders, so I suspect they are uncommon. There are a fair number of jackets around however that are also said to be "Dai", with distinctive hems that are either embroidered or decorated with parallel bands of recycled silk and other colored textiles. I attach a picture of one of these. The motifs seem to relate more to Chinese decorative traditions, in comparison with the skirts.
Thanks also for the identification of the Ha dialect jacket!