The answer is Food shortage.
The neolithic era began when some groups of humans gave up their pneumatic hunter gatherer lifestyle completely to the beginning farming. It may have taken humans hundreds or even thousands of years to transition fully from the lifestyle of subsisting on wild plants to keeping small gardens and later trending large crab feilds.
The two types of sources are maps and artifacts
Nationalist leader Jiang was fighting a civil war against communists led by Mao.
Answer:
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Explanation:
The Dust Bowl was caused by several economic and agricultural factors, including federal land policies, changes in regional weather, farm economics and other cultural factors. After the Civil War, a series of federal land acts coaxed pioneers westward by incentivizing farming in the Great Plains.