Greek history (X)

4th century:

Greece thus entered the 4th century under a Spartan hegemony, but it was clear from the start that this was weak. A demographic crisis meant Sparta was overstretched, and by 395 BC Athens, Argos, Thebes, and Corinth felt able to challenge Spartan dominance, resulting in the Corinthian War (395-387 BC). Another war of stalemates, it ended with the status quo restored, after the threat of Persian intervention on behalf of the Spartans.

Delian League,  before the Peloponnesian War 

The Spartan hegemony lasted another 16 years, until, when attempting to impose their will on the Thebans, the Spartans suffered a decisive defeat at Leuctra in 371 BC. The Theban general Epaminondas then led Theban troops into the Peloponnese, whereupon other city-states defected from the Spartan cause. The Thebans were thus able to march into Messenia and free the population.
Deprived of land and its serfs, Sparta declined to a second-rank power. The Theban hegemony thus established was short-lived; at the Battle of Mantinea in 362 BC, Thebes lost her key leader, Epaminondas, and much of her manpower, even though they were victorious in battle. In fact such were the losses to all the great city-states at Mantinea that none could establish dominance in the aftermath.

The weakened state of the heartland of Greece coincided with the Rise of Macedon, led by Philip II. In twenty years, Philip had unified his kingdom, expanded it north and west at the expense of Illyrian tribes, and then conquered Thessaly and Thrace. His success stemmed from his innovative reforms to the Macedon army. Phillip intervened repeatedly in the affairs of the southern city-states, culminating in his invasion of 338 BC.
Decisively defeating an allied army of Thebes and Athens at the Battle of Chaeronea (338 BC), he became de facto hegemon of all of Greece, except Sparta. He compelled the majority of the city-states to join the League of Corinth, allying them to him, and preventing them from warring with each other. Philip then entered into war against the Achaemenid Empire but was assassinated by Pausanias of Orestis early on in the conflict.
Alexander, son and successor of Philip, continued the war. Alexander defeated Darius III of Persia and completely destroyed the Achaemenid Empire, annexing it to Macedon and earning himself the epithet 'the Great'. When Alexander died in 323 BC, Greek power and influence was at its zenith. However, there had been a fundamental shift away from the fierce independence and classical culture of the poleis—and instead towards the developing Hellenistic culture.