One of the remarkable aspects of the Hellenistic era was the extent to which the people of Greece and the Middle East started exploring beyond the confines of the ancient world as they had known it. The Ptolemies supported trading posts along the Red Sea and as far south as present-day Eritrea and Ethiopia, trading for ivory and gold from the African interior. Explorers tried, but did not quite succeed, to circumnavigate Africa itself. In addition to accounts by explorers, the Greeks of the Hellenistic lands enjoyed histories and accounts of foreign lands written by the natives of those lands. Major histories of Mesopotamia, Persia, and Egypt were written during the Hellenistic period and translated into Greek. Ambassadors from the Hellenistic kingdoms in foreign lands sometimes wrote accounts of the customs of those lands (such as India). In short, it was a period when knowledge of the world greatly expanded.
The core of the Hellenistic kingdoms were the new cities founded by Alexander or, later, by the Hellenistic monarchs. The largest was Alexandria in Egypt, but there were equivalently grandiose cities in the other kingdoms. Both the new cities founded by Alexander and his successors and the old Greek settlements along the eastern coasts of the Mediterranean grew and prospered. The new cities were built on grid-pattern streets with various Greek amenities like public forums, theaters, and temples. Likewise, citizenship, which had been the basic unit of political currency in the ancient poleis, became instead a mark of elite membership that could be won in multiple cities at the same time; the important thing was either being descended by from Greek colonists or being a high-ranking “native” who was useful to the Hellenistic monarch.
Of note is the fact that the Seleucid cities represented the first major experiment in what we now call the welfare state. Because of the obligations the first monarchs felt toward their specifically Greek subjects, things like education and garbage collection were funded by the state. Eventually, public services extended to include poor relief, which consisted of free food distributed within the cities to the poorest classes of permanent residents. This practice had nothing to do with charity; it was simply a means for keeping the peace in the growing cities.
There were major ongoing problems for the Hellenistic ruling class, however, the most important of which was the continued stratification between Greeks and their non-Greek subjects. Greeks in the Hellenistic kingdoms felt that they were the heirs to Alexander’s conquests and that they were thus justified in occupying most, if not all, of the positions of political power. Especially in places like Egypt and Mesopotamia that had enormous non-Greek populations, resentment could easily turn into outright rebellion. Various works emerged among the subjects of the Hellenistic kingdoms predicting the downfall of their Greek rulers; Mesopotamian priests, Zoroastrians in Persia, and Egyptian religious leaders all wrote works of prophecy claiming that the Greeks were in league with evil forces and would eventually be deposed. The Jews also struggled with their Greek overlords, a problem exacerbated by the fact that they were ruled first by the Ptolemies and then by the Seleucids. While the Ptolemaic kingdom remained relatively stable until its takeover by the Romans in 30 BCE, both the Antigonid and Seleucid kingdoms lost ground over the years, ultimately ruling over a fraction of their former territories by the time the Romans began encroaching in the second century BCE.