The Greeks were part of the Ottoman Empire, who had different religion and culture, for centuries, and they had to pay high taxes but they were excluded from state administration jobs. With this situation, they revolutionized against the Ottoman Empire:
First, in 1822 Greeks declared independence, although it wasn't recognized by the Turnks. Five years laters, the Greeks won thanks to French and British military intervention. In 1830 the Ottoman Empire recognized the independence of Greece.