Major centers of domestication of plants and animals are Southwest Asia which also known as the Fertile Crescent, Southeast Asia, and the Americas. Plants and animals diffused globally because of the interaction of different cultures with each other. When the two different cultures interact with each other through migration from one region to the new one, both cultures exchanges some of the ways of living and methods. When the English people came to the New world, they introduced cultivation of corn crop which leads to diffusion of plants in the America.
As the resources in the world are distributed unequally, the crops and the ability to grow them in specific environmental conditions such as near the river valleys, on the foothills of the mountains and near the flood plains differ worldwide as many places don't have enough sunlight,
many places is too warm or hot for there growth and other place are too cold or are locates at great heights. Variation thus exists in the cropping patterns and the cropping intensity as they need specific conditions as climate, weather, and soil properties.
Many of the earlier civilizations developed and prospered near the river valleys.
