How did tofu come from?

There are different opinions about the origin of tofu, but most people think that it started with Liu An, the grandson of Liu Bang, the ancestor of the Western Han Dynasty. Liu An, known as the King of Huainan, has a mother who likes to eat soybeans. One day, her mother was ill in bed. King Huainan ordered people to grind soybeans into powder and add water to make soup for her to drink, but she was afraid that the food was tasteless, so she added some salt to taste. I didn't expect to condense into pieces, which is the formation of the initial prototype of tofu. Because Liu An was an alchemist, when the prototype of tofu was made, he used the alchemist to do experiments. After many studies, he finally found that gypsum or salt can solidify soybean milk into tofu, which is very delicious for cooking, and tofu began to spread among the people.