Ever since the beginnings of civilization, a process of expansion has been underway. Dramatic increases in the pace of expansion have frequently been stimulated by invasions and conquest of the civilized center by warlike peoples on the periphery of civilization. We have seen that process repeated over and over again. Sargon conquered the independent Sumerian city-states and created an empire in 2331 B.C.E. In so doing, the area of the civilized center was expanded to the north in the Tigris-Euphrates valley. Cultural diffusion then occurred between the different peoples of the area. The process was continued by the migration of the Amorites, a Semitic people from the Arabian peninsula, into the river valley, where they founded Babylon as the center of a larger empire.
A similar process had been occurring in the Nile valley to create the Egyptian Empire. The migration or invasion of the Hyksos people set the stage for the subsequent development of the New Kingdom, which, in about 1500 B.C.E., established an empire reaching into the fertile crescent.
During the the 8th Century, B.C.E., the Assyrians, migrating southward from the northern regions of the Tigris-Euphrates, conquered the civilized center and created an empire which included both Egypt and Babylonia. In the 6th Century B.C.E., the Medes and the Persians, migrating in from the Iranian plateau into the civilized center, created the Persian Empire, which included , not only the entire area of the old Assyrian Empire, but Iran and Anatolia as well.
Meanwhile, the once-independent Greek city-states, which had expanded their influence throughout much of the Mediterranean basin, were conquered and united by the Macedonians, coming into the Ionian peninsula from the north. Thus it was that the Greco-Macedonians were poised to conquer the Persian Empire.
Alexander's conquests would expand the civilized center from the eastern Mediterranean to the Indus river in India and permit the development of Hellenistic culture. The name derives from the fact that Greek culture spread throughout the area in the last 3 centuries before the common era.
In the Hellenistic period, although the cities were no longer independent, as they had been in the Hellenic era, they were the centers of trade and craft industry. It was in the cities that the descendants of the Greco-Macedonian conquerors became a professional class of rulers and soldiers and merchants, which provided a cultural and economic bond throughout the area, even though political unity did not survive the death of Alexander. Among the Greek ruling class, the old loyalties to the Polis had given way to a dedication to the profession. As the administrators and the merchants of their world, in spite of being in the minority, they had an influence out of proportion to their numbers. The city of Alexandria, founded by Alexander, located on the Mediterranean at the mouth of the Nile, became the most prominent center of commerce and learning. The library in Alexandria became the depository for recording many of the literary and scientific achievements of the time.
Although women continued to have a subordinate status, some lucky few of the wealthy and ruling classes, would have the opportunity to become involved in commerce or in intellectual activities. For the most part, however, women had no part in public life.
Slavery, which had been a commonly accepted practice throughout the history of ancient civilization, remained a prominent part of Hellenistic culture. Most labor was hand labor, and slavery had the effect of degrading the value of labor and discouraging the search for alternative methods of production. Thus, in spite of the fact that the Hellenistic era is noted for its scientific achievements, the increase in theoretical knowledge did not lead to practical applications. Industry remained essentially hand-craft industry, and agriculture remained the primary occupation. Trade and commerce, though enhanced by the mercantile and shipping expertise of a professional class of merchants, was limited, almost entirely to agricultural products such as the grains of the river valleys, and wine and olives of the Mediterranean.