Mesopotamia's greatest influence on future civilizations was the spread of agriculture. The region, located in the fertile area between the Tigris and Euphrates Rivers, was excellent for farming. Once irrigation was developed, the long growing season here could be properly utilized. Thanks to agriculture, populations grew due to the abundance of food. This led to a need for more laws and governance in order to ensure that society did not break down. People could now stay in one place—instead of putting their energies into migration, they could develop architecture. The people living in this region developed city walls and ceremonial ziggurats. People could also save part of the harvest for future planting. These people did not know it at the time, but they were selecting crops for future use based on genetics; this is something that farmers do even today. Mesopotamian agriculture is the region's most lasting legacy because, without it, all other advances would not have been possible.
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