Wine was invented by Du Kang and originated in Xia Dynasty. One day, Du Kang wanted to develop a drink, but he couldn't figure out how to make it. He had a strange dream when he slept at night. He dreamed that an old man with handsome hair came to him and said to him, "You take water as the source and grain as the material, and then on the ninth day when the grain is soaked in water, find three people, each of whom takes a drop of blood and adds it." Then the old man disappeared.