Explanation:
As early people began farming the Fertile Crescent, small villages began to form. With the further development of farming, many of these small communities began to grow into large, complex cities. Located in present day Iraq, the Fertile Crescent is a “half moon” shaped area that lies between two rivers.
https://study.com/academy/lesson/how-geography-isolated-ancient-china.html
That video will explain everything. I have already learned this in school, and it is very important on the test. VERY IMPORTANT.
Horizontal lines of latitude that run across the globe are known as A. parallels.
Two ecozones would be different it they had two different climates