The development of two great civilizations in the Middle East and North Africa is a frequent topic of comparative analysis. Due to totally dissimilar geography, dissimilar exposure to invasions by neighbors, and different set of beliefs, Egypt and Mesopotamia were in contrast to one another in many ways. Egypt developed a strong central authority. In contrast to this, the political environment of Mesopotamia evolved into a system of city-states. Mesopotamian art focused on a more literary approach with pictures and seals. Egyptian civilization is well known for its monuments.