How did Mesopatamnia's fertile soil affect the growth of civilizations in the area?

While Mesopotamia's soil was fertile the region's semiraid climate didn't have much rainfall with less than ten inches annually .

(202 bc - 220 ad) dynasty started by lui bang; a great and long-lasting rule, it discarded the harsh policies of the qin dynasty and adopted confucian principles; han rulers chose officials who passed the civil service exams rather than birth; it was a time of prosperity

honestly you should get that checked out because it really isn't normal