Greece has a history stretching back almost 4,000 years. The people of the mainland, called Hellenes, organized great naval and military expeditions and explored the Mediterranean and the Black Sea, going as far as the Atlantic Ocean and the Caucasus Mountains. One of those expeditions, the siege of Troy, is narrated in the first great European literary work, Homers Iliad. Numerous Greek settlements were founded throughout the Mediterranean, Asia Minor and the coast of North Africa as a result of travels in search of new markets.
During the Classical period (5th century BCE), Greece was composed of city-states, the largest being Athens followed by Sparta and Thebes. A fierce spirit of independence and love of freedom enabled the Greeks to defeat the Persians in battles which are famous in the history of civilization-- Marathon, Thermopylae, Salamis and Plataea.
In the second half of the 4th century BCE, the Greeks, led by Alexander the Great, conquered most of the then known world and sought to hellenize it.
In 146 BCE Greece fell to the Romans. In 330 CE Emperor Constantine moved the Capital of the Roman Empire to Constantinople, founding the Eastern Roman Empire which was renamed Byzantine Empire or Byzantium by western historians in the 19th century. Byzantium transformed the linguistic heritage of Ancient Greece into a vehicle for the new Christian civilization.
The Byzantine Empire fell to the Turks in 1453 and the Greeks remained under the Ottoman yoke for nearly 400 years. During this time their language, their religion and their sense of identity remained strong.
On March 25, 1821, the Greeks revolted against the Turks, and by 1828 they had won independence. As the new state comprised only a tiny fraction of the country, the struggle for the liberation of all the lands inhabited by Greeks continued. In 1864, the Ionian islands were added to Greece; in 1881 parts of Epirus and Thessaly. Crete, the islands of the Eastern Aegean and Macedonia were added in 1913 and Western Thrace in 1919. After World War II the Dodecanese islands were also returned to Greece.
Source: Embassy of Greece, Washington, DC, USA