information:classification, information:highlighting, stylistic:style_transfer
Background

Ancient Greece had traditionally been a fractious collection of fiercely independent city-states. After the Peloponnesian War (431–404 BC), Greece had fallen under a Spartan hegemony, in which Sparta was pre-eminent but not all-powerful. Spartan hegemony was succeeded by a Theban hegemony after the Battle of Leuctra (371 BC), but after the Battle of Mantinea (362 BC), all of Greece was so weakened that no one state could claim pre-eminence. It was against this backdrop that the ascendancy of Macedon began, under king Philip II. Macedon was located at the periphery of the Greek world, and although its royal family claimed Greek descent, the Macedonians themselves were looked down upon as semi-barbaric by the rest of the Greeks. However, Macedon controlled a large area and had a relatively strong centralized government, in comparison to most Greek states.

Philip II was a strong and expansionist king who took every opportunity to expand Macedonian territory. In 352 BC he annexed Thessaly and Magnesia. In 338 BC, Philip defeated a combined Theban and Athenian army at the Battle of Chaeronea after a decade of desultory conflict. In the aftermath, Philip formed the League of Corinth, effectively bringing the majority of Greece under his direct sway. He was elected Hegemon of the league, and a campaign against the Achaemenid Empire of Persia was planned. However in 336 BC, while this campaign was in its early stages, he was assassinated.

Succeeding his father, Alexander took over the Persian war himself. During a decade of campaigning, Alexander conquered the whole Persian Empire, overthrowing the Persian king Darius III. The conquered lands included Asia Minor, Assyria, the Levant, Egypt, Mesopotamia, Media, Persia, and parts of modern-day Afghanistan, Pakistan, and the steppes of central Asia. The years of constant campaigning had taken their toll, however, and Alexander died in 323 BC.

After his death, the huge territories Alexander had conquered became subject to a strong Greek influence (Hellenization) for the next two or three centuries, until the rise of Rome in the west, and of Parthia in the east. As the Greek and Levantine cultures mingled, the development of a hybrid Hellenistic culture began, and persisted even when isolated from the main centres of Greek culture (for instance, in the Greco-Bactrian kingdom).

It can be argued that some of the changes across the Macedonian Empire after Alexander's conquests and during the rule of the Diadochi would have occurred without the influence of Greek rule. As mentioned by Peter Green, numerous factors of conquest have been merged under the term Hellenistic period. Specific areas conquered by Alexander's invading army, including Egypt and areas of Asia Minor and Mesopotamia "fell" willingly to conquest and viewed Alexander as more of a liberator than a conqueror.

In addition, much of the area conquered would continue to be ruled by the Diadochi, Alexander's generals and successors. Initially the whole empire was divided among them; however, some territories were lost relatively quickly, or only remained nominally under Macedonian rule. After 200 years, only much reduced and rather degenerate states remained, until the conquest of Ptolemaic Egypt by Rome.