1、 What do you mean

Grain refers to wheat, corn, rice, soybeans and potatoes, but it is also customary to call grains other than rice and flour as coarse grains, and coarse grains also refer to grain crops in general. Therefore, grain is also the general name of grain crops

2、 Historical origin

The saying of grains and miscellaneous grains has a very long history. The Chinese people have followed the diet dominated by grains for thousands of years, which was mentioned in the book of the Yellow Emperor's Internal Classic in 2000. It is generally believed that wheat and rice are fine grains, and coarse grains refer to other grains. What we call coarse grains now includes a variety of cereals and legumes, such as corn, millet, barley, black beans, broad beans, mung beans, peas, sweet potatoes and so on