It is not common to find good protein sources in the vegetarian diet, but like a ray of hope comes soyabean. It is now a widely used ingredient all over the world.
Nothing concrete can be pointed out as far as dates are concerned, but China can surely be credited with introducing this wonder along with many forms of soybean to the world.
Soyabean has been used since time immemorial as an important source of protein in Chinese cuisine.
From the botanical perspective
Soyabean is a type of legume from the leguminoseae family. It is a bean like kidney beans, cluster beans with ample amount of proteins. It is a hard bean and needs soaking before it can be used as food. The kernels need to be softened in the process.