When soybean flour is put in contact with warm water it creates a rich, softening milk that will soothe the skin and condition the hair.
Although botanists haven't entirely agreed on the origins of the soya bean (Glycine soja), it is believed that the plant derives from a Chinese legume, glycine ussuriensis. Soya has been eaten and cultivated in China since 2800BC, and it was considered one of the five substances essential for living.
Today, the USA is the main grower of soya, and over 90% of the crop is used for animal feed. A whole soya industry has developed around the bean and various materials made from it are widespread today (milk, oil, sauce, tofu, etc.).