There was a lot of unity at first, then war. This period was during Alexander the Great's conquests and also after his death, when many generals and groups tried to claim power.After 40 years, four major monarchs came into power in four separate regions, each using fighting and force to maintain their domains.
Interaction with Environment
The expansion done by Alexander the Great put many resources under the use of the Hellenistic Empire, including agriculture, bodies of water, gold and silver, and various animals.
When Alexander first united the regions, it broke down trade barriers and increased money circulation. Also, with the conquest of Persia, a lot of gold and silver was released into the economy, which first made prices rise sharply, then slowly go down. Lastly, the expansion of land meant expansion of trade routes, which meant trade opened up with China, Arabia, East Africa, and India.
Armies were specially trained and equipped with tools like sarissas (spears), as well as helmets, leather corsets, and shields. They used a formation called the phalanx, which was basically impenetrable from the front, but couldn't move quickly and was more vulnerable from other sides. Nonetheless, they were a very large and equipped military force.
A lot of Greek art was characteristic of this time, moving from idealistic (during the Greek city-state times) to realistic. Depictions of men are found in both art and literature, with themes of their everyday life and emotions.
There was a lot of interaction between all the people that had been combined into one empire from Alexander's conquest. Into the Hellenistic empire, these interactions continued, and Greek culture intermingled with that of the other eastern territories.
Architecture was further developed and refined into classical styles. They created temples, public buildings, and monuments.
They made many advancements in education, mainly in the science field with revelations by people like Euclid, Archimedes, and Eratosthenes.
There were three main philosophies: Stoicism, which taught that the wise were to be praised and above any pleasure or pain; Epicureanism, which taught that pleasure and niceties were to be chased after; and Skepticism, which taught that some knowledge is impossible to gain.