Which factor most contributed to the growing economies of Mesopotamian Empires?

Climate

Explanation: Mesopotamian economy depended on trade. They mostly traded crops, pottery, cheese, and other goods. The climate made for great farming and the fertile crescent was born! Also, without worrying about food, people could also focus on other things such as law. For example, ever heard of Hammurabi's laws? A tablet with the world's first-ever written laws of a strict social hierarchy.