Record of what a guy born in Korea and living in USA reads in his 40s.
As a result of Columbian Exchange, American crops such as maize (or called corn) and sweet potato were introduced to China, saved the stomachs of many hungry people, and resulted in a population boom. On the other hand, deforestation of mountains for growing the American crops resulted in soil erosion, less stable water supply to rice pads in the valleys, more floods, and eventually decline of the whole China. On the contrary, American crops, especially potato, spelled an end to famine in Europe and enabled it to dominate the world. Why did the same American crops drive China and Europe in the opposite directions respectively?