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 demographics of the region toward increased ethnic homogenization within the territories each respective country ultimately was awarded. This was followed by the large-scale Greek-Turkish population exchanges of 1923 (Treaty of Lausanne), which finalized the reversal of Western and Eastern Thrace region's pre-Balkan War demography. The treaty granted the status of a minority to the Muslims in Western Thrace, in exchange for a similar status for the ethnic Greek minority in Istanbul and the Aegean islands of Imbros and Tenedos. After the German invasion (April 1941), the area was occupied by Bulgarian troops, as part of the triple Axis occupation of