The reasons are as follows:

Most people in Ningxia wear a kind of hat called a little white hat. It's said to be a little white hat, but it's actually lavender.

It is determined by religion, climate and various reasons. This is mainly related to Islam. When the Hui people kowtow in worship, their foreheads and nose tips must touch the ground. For convenience, they wear brimless purple hats, also known as small white hats.