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 of multiple ethnic groups. However, Recep Tayyip Erdoğan, during his historic December 7, 2017 visit to Greece as President of Turkey, acknowledged for the first time the multi-ethnic nature of the Muslim minority. The last censuses which asked about ethnicity were held in the transitional period before the region became part of Greece. A number of estimates and censuses during the 1912-1920 period gave the following results about the ethnic distribution of the area that would become known as Western Thrace: The Pomak population depending on the source was sometimes counted together with the Turks (Muslims) following the Ottoman system