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,
Diocese of Thrace Diocese of Thrace The Diocese of Thrace (, ) was a diocese of the later Roman Empire, incorporating the provinces of the eastern Balkan Peninsula (comprising territories in modern south-eastern Romania, central and eastern Bulgaria, and Greek and Turkish Thrace). Philippopolis (modern Plovdiv, in Bulgaria) was the capital. The diocese was established as part of the reforms of Diocletian and Constantine the Great, and was headed by a "vicarius" subordinate to the praetorian prefecture of the East. As outlined in the "Notitia Dignitatum" of ca. 400, the diocese included the provinces of Europa, Thracia, Haemimontus, Rhodope, Moesia II and Scythia