The hometown of walnuts is Iran in the west of Asia. After the Han dynasty, Zhang Yan brought the Western Regions back to China.
1, according to the classification of origin, there are Chencang walnuts, Yang Ping walnuts, wild walnuts;
2, according to the maturity classification, there are summer walnut, autumn walnut;
3, according to the degree of smooth shell classification, light walnut, hemp walnut;
4. There are two types of shell thickness classification, namely thin shell walnut and thick shell walnut.