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,
Turks of Western Thrace usually insisted that the basis of identification of a minority is religious and not ethnic (or national). Thus Greek officials refer to the Muslim minority in Greece as Greek Muslims, who were based mainly in Western Thrace. Muslim communities also lived in Greek Macedonia, Epirus, and Crete (see Cretan Turks) and were the descendants of Ottoman-era Greek converts to Islam who joined the Turkish Millet (Ottoman Empire). However, these particular communities were relocated from Greece to Turkey following the Population exchange signed between the two countries in 1922-23, with only the Greek Muslims of Western Thrace exempted from it. Successive