Mesopotamia consisted of a series of Empires, either Sumerian, Babylonian, or Chaldean, to name a few. Each was ruled by an Emperor with a well defined class structure which separated the nobility from the commoners. Among the more well known of the Mesopotamian Emperors was Hammurabi, who promulgated his famous Code of Laws, and Nebuchadnezzar, who constructed the hanging Gardens of Babylon. This system remained in place until the area was ultimately conquered by the Persians under Cyrus the Achaenamid in 558 B.C.E.
Ancient Egypt was ruled by a king known as the Pharaoh, meaning "Great House." He was considered the personification of the sun God, Horus, and was believed to be responsible for the annual flooding of the Nile, from which ancient Egypt gained it subsistence. Pharaoh ruled directly through an administrative bureaucracy; there was no Egyptian nobility. Although some Pharaohs led troops into battle, most were never seen by the public at large. They remained secluded from public view. It was forbidden to even look on him, and to touch him unless he expressly requested it was punishable by death. Pharaohs typically referred to their wives as their "dear sister." This has led to some speculation that these marriages were incestuous, but there is no concrete evidence.
The early society of India was the Harappan, or Dravidian. Because their language has not yet been deciphered. As a result, there is no way of knowing their political structure. It is known that they built several large cities with broad streets organized on a grid with shops, public baths, and other amenities. All of this indicates a highly organized and developed society; but other than that, nothing is known of their system of government.