Early civilizations first emerged along major river valleys, such as in Mesopotamia between the Tigris and Euphrates Rivers, as well as in ancient Egypt and China. These civilizations were characterized by strong centralized governments, hierarchical societies organized around irrigated agriculture. Writing was developed independently in many early civilizations, often using symbols pressed into wet clay, which allowed them to more effectively organize politically and count resources. Society in early Mesopotamia featured a privileged aristocracy and priests, with underprivileged peasants and craftsmen lacking many rights, including women and slaves. Cities had surrounding walls and prominent ziggurat temples, and contributed innovations including the first written language of cuneiform, early