their political systems were far less developed too, and although Egyptian religion had taken root in most of the communities of Upper and Lower Egypt temples had yet to reach their characteristic grandiose size until the pharaonic period. The rise of the great pharaohs meant an enormous boost in wealth and political power to the demigod/kings who could commission the large architectural projects that epitomize dynastic Egypt. During the Old Kingdom, massive pyramids flanked the Giza plateau, and later tombs and temples proved the might of pharaonic wealth and power. Egypt was therefore easier than Mesopotamia to manage and control under one centralized government because prior to the first King Menes, Egypt was comprised of relatively small and simple agricultural villages. Mesopotamia, on the other hand, was made up of city-states that had substantial wealth and power bases as well as centers of learning and technology. It is naturally easier to unify a series of already interdependent villages than a network of rival city-states. The unification of Lower and Upper Egypt proved enormously successful for several reasons. First, the centralized theocratic government imposed one state religion that in turn became a major source of social order. In Mesopotamia, the city-states had unique identities that might have precluded religious unification. Second, a centralized government in Egypt enabled control of the Nile delta for economic purposes. To do so in Mesopotamia would have been more difficult given the more varied geographic terrain and the presence of more than one river. Similarly, Egypt was less vulnerable to foreign invaders than Mesopotamia was. Geography therefore played a major role in determining the differences between ancient Mesopotamia and Egypt.

Egypt's system of language and writing; their sophisticated systems of astrology and calendar-making; and their technological developments all followed from unification. Unification allowed cultural flourishing to take place primarily by increasing economic prosperity. In Mesopotamia, on the other hand, systems of writing and language; technology and science...

The city-states were already fairly prosperous and thus did not attribute their prosperity or their learning to the central government but to their local histories.
Ancient Mesopotamia was relatively diverse socially, especially when compared with ancient Egypt. Semetic and non-Semetic languages of Mesopotamia were based on similar phonemes but individual city-states developed their languages and later, systems of writing, differently from one another. Their differences created unique cultural identities for Mesopotamian city-states. In Egypt, a common language evolved and only after unification did hieroglyphs and other emblems of Egyptian culture emerge. The Egyptian people began viewing themselves as a unified culture as the society evolved organically, as a whole. In Mesopotamia, cultural evolution took place long before unification was possible. Unification failed to give Mesopotamian people new identities or reasons to identify with a distant centralized government. Mistrust of neighboring city-states also led to the eventual dissolution of the Mesopotamian central government that Sargon initiated.

By the time of Alexander the Great, the Egyptian empire was showing signs of decline. A series of foreign kings weakened the cohesive society that Egypt depended on for the strong sense of unity between the various cities along the Nile. As foreign cultures and powers encroached on Egypt, and as dynastic power weakened, the region fell sway relatively easily to the Achaemenid Persian Empire. The Persian Empire also encroached on Mesopotamia. Without a centralized government to help mobilize troops to fend off the Persians, Mesopotamian city-states gradually weakened.

Whereas ancient Mesopotamia is mainly a history of disparate city-states that often vied for wealth, power, and control of natural resources, ancient Egypt remained a unified kingdom for several thousand years. The differences between how the two regions developed can be traced to pre-written history of the two regions, which developed differently. Mesopotamia developed earlier than Egypt, and city-states were powerful and self-sufficient by the time any king attempted to unify the region. History, politics, and culture all played major roles in determining the success of unification in Egypt and Mesopotamia.