Albanian-speakers of Western Thrace migrated towards today's European Turkey (Eastern Thrace), especially near Istanbul. Many Muslim Albanians achieved high office in Ottoman society and many of them, most notably the Köprülü family, became Grand Viziers of the Empire. The majority of the Albanian emigration came from Northern Kosovo and the Korça region of Albania. Descendants of this immigrants would later play an important role in the National Renaissance of Albania. The number of Albanians that resided in the region is unknown, as statistical data of the Ottoman Empire were based on religious identification (millets). Thus, the Orthodox Albanians were part of the Rûm millet,
Western Thrace forced respective minority populations in the Thrace region out of areas they controlled. A large population of Greeks in Eastern Thrace, and Black Sea coastal and southern Bulgaria, was expelled south and west into Greek-controlled Thrace. Concurrently, a large population of Bulgarians was forced from the region into Bulgaria by Greek and Turkish actions. Turkish populations in the area were also targeted by Bulgarian and Greek forces and pushed eastward. As part of the Treaty of Neuilly, and subsequent agreements, the status of the expelled populations was legitimized. This was followed by a further population exchange which radically changed the