Classical Greece was a 200 year period in Greek culture lasting from the 5th through 4th centuries BC. This classical period had a powerful influence on the Roman Empire and greatly influenced the foundations of the Western Civilization. Much of modern Western politics, artistic thought, such as architecture, scientific thought, literature, and philosophy derives from this period of Greek history. In the context of the art, architecture, and culture of Ancient Greece, the Classical period, sometimes called the Hellenic period, corresponds to most of the 5th and 4th centuries BC (the most common dates being the fall of the last Athenian tyrant in 510 BC to the death of Alexander the Great in 323 BC). The Classical period in this sense follows the Archaic period and is in turn succeeded by the Hellenistic period.
From the perspective of Athenian culture in Classical Greece, the period generally referred to as the 5th century BC encroaches slightly on the 4th century BC. This century is essentially studied from the Athenian outlook because Athens has left us more narratives, plays, and other written works than the other ancient Greek states. In this context, one might consider that the first significant event of this century occurs in 510 BC, with the fall of the Athenian tyrant and Cleisthenes' reforms. However, a broader view of the whole Greek world might place its beginning at the Ionian revolt of 500 BC, the event that provoked the Persian invasion of 492 BC. The Persians (called "Medes") were finally defeated in 490 BC. A second Persian attempt failed in 481-479 BC. The Delian League then formed, under Athenian hegemony and as Athens' instrument. Athens' excesses caused several revolts among the allied cities, all of which were put down by force, but Athenian dynamism finally awoke Sparta and brought about the Peloponnesian War in 431 BC. After both forces were spent, a brief peace came about; then the war resumed to Sparta's advantage. Athens was definitively defeated in 404 BC, and internal Athenian agitations mark the end of the 5th century BC in Greece.
Since the beginning, Sparta had been ruled by a "diarchy." This meant that Sparta had two kings serving concurrently throughout its entire history. The two kingships were both hereditary and were either from the Agiad dynasty or the Eurypontid dynasty. Allegedly, the hereditary lines of these two dynasties spring, respectively, from Eurysthenes and Procles, twin descendants of Hercules. Eurysthenes and Procles were said to have conquered Sparta two generations after the Trojan War.
In 510 BC, Spartan troops helped the Athenians overthrow their king, the tyrant Hippias, son of Peisistratos. Cleomenes I, king of Sparta, put in place a pro-Spartan oligarchy headed by Isagoras. But his rival Cleisthenes, with the support of the middle class and aided by democrats, managed to take over. Cleomenes intervened in 508 and 506 BC, but could not stop Cleisthenes, now supported by the Athenians. Through his reforms, the people endowed their city with isonomic institutions—i.e., ones that all have the same rights—and established ostracism.
The isonomic and isegoric democracy was first organized into about 130 demes, which became the foundational civic element. The 10,000 citizens exercised their power via the assembly (the ekklesia, in Greek) of which they all were part, headed by a council of 500 citizens chosen at random.