The Hellenistic Period marks the period between Alexander the Great’s death in 323 BCE and the rise of the Roman Empire in 31 BCE. It is often a term used by historians to locate extensive Greek expansion and colonization across the continents of Africa and Asia set in motion by Alexander’s father, King Philip II (d. 336 BCE), who ruled the Greek city-state of Macedonia.

As a ruler, King Philip II attempted to conquer Persia although he was assassinated in 336 BCE before he could complete his mission. Alexander took over his father’s reign and lead an army to conquer Persia, Anatolia, Syria, Phoenicia, Judea, Gaza, Egypt, Bactria, and Mesopotamia. Through these conquests, Greek culture spread and fused with other cultures, and new languages such as the Koine Greek and new religions and gods emerged. With a new common dialect, communication became easier and this led to the spread of ideas to new territories. This also assisted in making trade across the Hellenistic kingdoms easier. After Alexander died, his empire was left to his generals who separated and ruled different parts of the kingdom: Ptolemy ruled Egypt and parts of the Middle East, Seleucus controlled Syria and the Persian Empire, and Antigonus and his son Demetrius ruled over parts of northern Asia Minor. These kingdoms fought one another in the attempt to establish their own power, which lasted for several centuries until the Ptolemaic Kingdom fell to Rome in 31 BCE.

The Hellenistic Period witnessed development in the areas of religion, architecture, science, and philosophy. The conquests opened up an interchange of religious beliefs and ideas. New people joined cults around the goddess Isis and the Orphic and Eleusinian mystery cults. New devotees worshiped the Egyptian mother-goddess Isis while the astral religion of the Chaldeans spread rapidly. Oriental cults focusing on female deities were worshiped by believers in frenzied rites of self-mutilation. There was also nationalistic and messianic resistance to the Hellenization of religion when rebels fought against the encroachment on cherished traditions. The influences of Hellenistic religions extended beyond the end of the era and all the way into the fourth century CE during the time of Emperor Constantine.

The Hellenistic period also produced sophisticated and elaborate architectural designs and structures. New complex buildings and monuments were built on a larger scale. Many palaces, mansions, and public monuments portrayed prestige and wealth. The large Mausoleum of Pergamon and the imposing lighthouse of Alexandria were some of the more advanced structures of this period.

There was flourishing within philosophical thought. Several schools of thought, notably the Stoics, Skeptics, and Epicureans, became active and presented ideas on the ethical and metaphysical nature of human existence. According to Epicurus (d. 270 BCE), the most important thing in life is the pursuit of pleasure and happiness, and the highest good is the serenity of the soul and the absence of mental and physical pain. The Epicureans, who derived their metaphysics from Democritus, were materialistic because they denied the existence of spiritual substances. Epicurus believed that the basic property of all things are indivisible atoms and that change and growth are the results of the combination and separation of these particles. On this view, the soul is a material entity that will not survive the death of the body. Neither did the gods intervene in human affairs. The Stoics emerged through Zeno (d. 262 BCE) and emphasized duty and self-discipline as cardinal virtues. They claimed that all men are brothers under the fatherhood of one God and urged participation in public affairs as a duty for the citizen of the rational mind. Skepticism, founded by Pyrrho (d. 270 BCE), taught that all knowledge is derived from sense perception and therefore must be both limited and relative. The skeptics argued that one could not prove anything and that because sense-impressions are deceptive people could never claim to be certain of the truth. They also believed that the most appropriate course of action in light of uncertainty is to suspend judgment as this leads to happiness. The Hellenistic period clearly witnessed a healthy and passionate exchange of philosophical ideas.

Science during the Hellenistic Period grew within the realms of astronomy, geography, medicine, physics, and mathematics. The astronomer Aristarchus of Samos (d. 230 BCE) discovered that the immobility of the “fixed” stars is due to their vast distance from the Earth. He also claimed that the Earth and other planets revolved around the sun although his teaching was not accepted because it conflicted with anthropocentric views of Greek thought and with the teachings of the philosopher Aristotle (d. 322 BCE). The astronomer Hipparchus (d. 120 BCE) invented the astrolabe and calculated the diameter of the moon as well as its distance from the Earth. Ptolemy of Alexandria (d. 170 BCE) was likely the last of the great Hellenistic astronomers and went to work systematizing the ideas of others before him. In mathematics and geography, Hipparchus (d. 120 BCE) laid the foundations of plane and spherical trigonometry. The mathematician Eratosthenes (d. 194 BCE) calculated the circumference of the Earth and created the first map of the world. Dissection of the human body was practiced by the physician Herophilus of Chalcedon (d. 280 BCE). Herophilus provided a detailed description of the brain and tried to explain the different functions of its various parts. He also discovered that arteries contained blood rather than a mixture of blood and air as Aristotle had thought previously. Herophilus also noted the heart to pump blood to different parts of the body. Archimedes (d. 212 BCE) discovered the law of floating bodies while also establishing the principles of the lever, the pulley, and the screw.

The Hellenistic period came to an end when the Roman Republic conquered the territories Alexander the Great once ruled. In 31 BCE, during the Battle of Actium, Octavian defeated Marc Antony’s Ptolemaic fleet which enabled him to consolidate Rome’s power in the region and over the sea.