Such round hats are head accessories for the Yi women after giving birth. With the shape of a round sack, these hats have a round cover which measures about 15 inches in diameter. In places such as Mianning, Yuesui, Yanyuan, etc., a soft cover is usually adopted, while a flat and hard cover like a disc is common in areas including Xichang and some places of Zhaojue. But the custom of wearing such a kind of hat after women giving birth has been discarded in some places such as Tianba and Zhuhei. In Zhuhei, women often put a piece of dented iron plate on their heads, and then cover it with many layer of cloth belts about four inches in width to form a head adornment style named “da pan tou”, literally meaning big wrapped head. Women who have not given birth to babies yet are also allowed to wear this kind of head adornment. It’s just that there are different rules for different social ranks. While Black Yi women can never have a wrapped head that is big enough, While Yi females’ wrapped heads should remain under a certain limit in size.
Quote from page 29 in A Research Report on the Yi People in Xikang by Zhuang Xueben