In the pre-Qin period, people washed their hair with the water that washed millet. The water for washing grain contains alkaline components, which helps to separate oil stains. At the same time, rich water-soluble vitamins and minerals also help to maintain the scalp and hair.

Gleditsia sinensis is a common tree in the north, and Gleditsia sinensis is the fruit of Gleditsia sinensis. Gleditsia sinensis is rich in saponin, which can be used as shampoo, hand sanitizer, shower gel and even laundry detergent after being mashed and added with water.

If you pay attention, you can peel off the skin and seeds of Gleditsia sinensis, dry the meat of Gleditsia sinensis in the sun, soak it in hot water when using it, and soak out the effective ingredients. The "Gleditsia sinensis soup" made from it is a good shampoo.

At the latest in the Southern and Northern Dynasties, Gleditsia sinensis has become a daily fast-moving consumer product, which has been completely commercialized and sold in ordinary shops.

Extended data:

How often did the ancients wash their hair? It is said that the ancients often did not wash their hair for a month. First of all, it is not as convenient as modern people to wash their hair.

Second, their hair is not as dirty as modern people, they eat lightly, and the air is not as dirty as it is now. Naturally, they don't have to wash their hair every three days like us.

Third, they really don't like washing their hair. I remember a passage in A Dream of Red Mansions in which Musk said that her head was itchy and Baoyu said that she would help her comb her hair. You should know that the grate is used to comb lice. As the first-class daughter of an ancient family, all have lice, and your son Baoyu doesn't feel wrong, which shows that the ancients really didn't like washing their hair.

Changping Popular Science Network-How did ancient people wash their hair?