Tourkokratia

Most of the areas which today are within modern Greece's borders were at some point in the past a part of the Ottoman Empire. This period of Ottoman rule in Greece, lasting from the mid-15th century until the successful Greek War of Independence that broke out in 1821 and the proclamation of the First Hellenic Republic in 1822 (preceded by the creation of the autonomous Septinsular Republic in 1800), is known in Greek as Tourkokratia (Greek: Τουρκοκρατία, "Turkish rule"; English: "Turkocracy"). Some regions, however, like the Ionian islands, various temporary Venetian possessions of the Stato da Mar, or Mani peninsula in Peloponese did not become part of the Ottoman administration, although the latter was under Ottoman suzerainty.

The Byzantine Empire, the remnant of the ancient Roman Empire which ruled most of the Greek-speaking world for over 1100 years, had been fatally weakened since the sacking of Constantinople by the Latin Crusaders in 1204.

The Ottoman advance into Greece was preceded by victory over the Serbs to its north. First, the Ottomans won the Battle of Maritsa in 1371. The Serb forces were then led by the King Vukasin Mrnjavcevic, the father of Prince Marko and the co-ruler of the last emperor from the Serbian Nemanjic dynasty. This was followed by another Ottoman victory in the 1389 Battle of Kosovo.

...
Wikipedia