Pyramids were also built in the Tigris and Euphrates River Valleys. Ziggurats are mounds of earth with distinctive spiral stairs around them. Ziggurats are mounds of earth distinguished by spiral stairs climbing their walls. They allow local elites to climb above seasonal floods. The height signifies the greater vision/knowledge and wisdom of priests. Grain silos also helped ensure loyalty during famines.
Agriculture may have begun in the Black Sea basin (flooded about 6,000 years before Christ). Refugee farmers fled west along the Danube, north along the Volga and east - over the Anatolian Plateau into the Fertile Crescent. Unfortunately, rains and spring floods do not coincide with grain growing seasons, so they needed to dig lengthy irrigation ditches to water crops. Since any single irrigation canal requires far more labour than a single village could provide, society became stratified and more complex. Subsistence farmers sold their children into slavery when threatened by famine.
Similarly, Mayan temples served as water reservoirs and were surrounded by complex irrigation canals.
What economic purpose did Egyptian pyramids serve?