Song people carefully recorded in Old Wulin, Volume 6, Little Broker, that there were already merchants specializing in "Soap Troupe" in Lin 'an, Kyoto in the Southern Song Dynasty. In addition to natural Gleditsia sinensis, plants such as Sapindus mukoraiensis have also spread among the people and become good cleaners.
Later, with the development of history and the progress of the times, they gradually invented soap. At that time, it was the idea put forward by Sun Simiao, a medical sage in the Tang Dynasty. The washed pig pancreas was air-dried and ground into powder, and then spiced bean powder was added to make it into a ball, which was the embryonic form of the original soap. In the Tang Dynasty, soap was called bath bean. People have been washing clothes in this way ever since.
During the Spring and Autumn Period and the Warring States Period in China, washing clothes was called "smashing clothes", and there was a saying that "the women in the East Village smiled and wore gauze in vain", which was the most common riverside washing. Washing boards and sticks are the main tools for washing clothes. Women who live near the water often beat with wooden sticks, and women who live far from the water invented washboards. The description of "Yi Dao" can be found everywhere in poets' poems, such as Li Bai's "A bright moon hangs high in the capital, and it is tempered".