Black Yi Lady and Her Maid

Skirts
Females of the Yi ethnic minority group wear pleated skirts instead of trousers. The length of skirts is an indicator of class. Those worn by Black Yi women, usually from noble families, are long enough to touch the ground, stirring a cloud of dust when the wearers walk, while the White Yi females, commoners in most of the cases, wear skirts that only stretch to ankles, allowing them to walk freely.
Girls would start wearing skirts at three or a little older, beginning with skirts made by stitching two pieces of cloth together and changing to those composed of three or four pieces of cloth after getting married or reaching adulthood. Local self-made cotton cloth is the main material for skirts, and in some cases a kind of rough and rigid local fabric called “mo zi” is adopted because of lower cost. Most of the skirts are in blue, white or dark brown and those in red or pink can also be seen in Tianba. The hem of skirts is usually decorated with two black strips with different width.
Skirts of great width, usually eight chi (equivalent to 8.75 feet) or more, made of three or four pieces of cloth, or two at least, are popular in Liangshan and Mianyue. For the bottoms worn by women in Mianyue, there are often four sections, the two below knees are in the shape of accordion pleats while the upper two are flatten in the shape of barrel. In comparison, skirts for women in Zhaojue are usually composed of three parts with the lower one in the shape of accordion pleats a complete piece, while those seen on women in Xichang are short and tight, with an even shorter section of pleats and a barrel-shape part that stretches to more than six inches below the knees.
Quote from pages 31&32 in A Research Report on the Yi People in Xikang by Zhuang Xueben