Roman Imperial Era: Greece experienced a new heyday during the imperial era. In the east, the »Hellenes« formed an upper class with special privileges since Augustus (requirement: attendance at grammar school).
The Greek element played an important role in local and regional administration, and since the 2nd century AD also in imperial administration. In addition to the provincial parliaments in the Greek East, the city and tribal alliances, which now also served the imperial cult and the representation of interests in Rome, remained in existence. The festival associated with the imperial cult and the building activity, which was promoted by the emperors as well as the “Homonoia contracts”, which sealed the harmony (Greek homónoia) between the cities, contributed to the economic prosperity of the communities. Greece itself was conquered by Augustus in 27 BC. Reorganized as the province of Achaia (capital Corinth). The return of freedom through Nero remained an episode. After Hellenism had been badly shaken under Trajan by the Jewish uprising (114–117), especially in Cyrene, Egypt and Cyprus, Hadrian sought to strengthen it by founding a Panhellenic covenant (which existed until the middle of the 3rd century).
The seat of the federation was Athens, which was then enlarged (Hadrian’s city) and made the cultural capital of the Greek half of the empire. The time was spiritually shaped by Plutarch, Dion from Prusa and the representatives of the “second sophistry”, who also had political influence. In the 3rd century there were several incursions by the Heruli, including Athens plundered (267; defensive success of Dexippus). Since Diocletian, Greece belonged to the Illyrian prefecture as the diocese of Macedonia with the provinces Epirus I and II, Macedonia, Thessalia and Achaia (Thessalonike was the residence of Galerius).
In the 4th and 5th centuries Athens flourished again as the center of the later sophistry (including the future emperor Julian Apostata studied there) and conveyed the Greek culture to the city of Constantinople and the Byzantine Empire.
In 1460 the Peloponnese (Morea) was conquered by the Ottomans. The rival trading powers Venice and Genoa (the latter with the possession of Lesbos 1355–1462 and Chios 1304–29 and 1346–1566) remained the only links after the conquest of the Byzantine Empire by the Ottomans (Constantinople fell in 1453, the Empire of Trebizond in 1461) between Greece and the West; both gradually lost their Greek possessions. Rhodes was evacuated by the Knights of St. John in 1523. Only Corfu and Zakynthos never came under Turkish rule, Kefallinia only 1479–1500.
After the Ottoman conquest, the country was largely attached to the governorship of Rumelia and divided into provinces (sanjaks), the governors of which were later often given the rank of pasha. In the middle of the 17th century, the Peloponnese (Morea) was raised to its own governorship, as was Crete, which was conquered in 1645–69. Some coastal areas and islands were subordinate to the Grand Admiral (Kapudan Pascha), the latter often having a special position and a certain autonomy. Until the 17th century, the non-Islamic population, who were granted the freedom to practice their religion with certain restrictions, generally enjoyed legal security and freedom of trade; the peasants retained their personal freedom; the tax burden and the boy reading for the recruitment of the Janissary Corps as well as officials and palace servants were not felt to be as oppressive as the earlier exploitation by the Venetians. After defending against the second siege of Vienna (1683), the Venetian admiral F. M. Morosini conquered in the course of the counter-offensive of the Christian powers against the Turks (1684-87)Athens (only for a few months) and the Peloponnese, which had to be ceded to Venice in the Treaty of Karlowitz in 1699 (with some islands); however, it became Turkish again through the Peace of Passarowitz in 1718, along with the island of Tenos (now Tinos); thus the entire Greek settlement area with the exception of the Ionian Islands and the island of Kythera, which belonged to Venice, became Turkish. In the Ecumenical Patriarchate, which was also endowed with extensive secular powers, the Sultan had recognized a kind of Greek national representation; Greeks from the noble families of the Constantinople district of Phanar (Phanarioten) rose to high administrative posts in the Ottoman Empire.
Due to the internal crisis of the Ottoman Empire since the 17./18. Century and especially as a result of the financial crisis, v. a. the peasants under increasing tax pressure; Fled peasants and other dispossessed and persecuted people united in the band of robbers of the Klephts to form a form of national and social resistance. From them and the mostly Christian militias of the Armatols emerged a military leadership class that played an important role in the Greek struggle for freedom. The appearance of a Russian fleet during the Russo-Turkish War 1768-74 (Turkish wars) in the Mediterranean and the landing of Russian troops in the Peloponnese in 1770 led an uprising but was also depressed as that of the Sulioten 1803. In the peace treaty of 1774, Catherine II obtained the right to withdraw from collaborators and their families who were willing to leave the country and settled them in the newly acquired southern Russian territories (numerous cities were founded with the suffix -pol).