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,
Thrace With the fall of the Western Roman Empire, Thracia turned into a battleground territory for the better part of the next 1,000 years. The surviving eastern portion of the Roman Empire in the Balkans, later known as the Byzantine Empire, retained control over Thrace until the 8th century when the northern half of the entire region was incorporated into the First Bulgarian Empire and the remainder was reorganized in the Thracian theme. The Empire regained the lost regions in the late 10th century until the Bulgarians regained control of the northern half at the end of the 12th century. Throughout