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,
Provisional Government of Western Thrace along a ridge of the Rhodope mountains running west of Daridere and east of Madan up to the Bulgarian-Greek border. After the retreat of both the Bulgarian and Greek armies an autonomous state was declared with Ottoman support, in order to avoid Bulgarian rule after the Treaty of Bucharest, in which the Ottomans had not taken part. Under British pressure, the Bulgaria and the Ottomans signed the Treaty of Constantinople, which satisfied the Turkish claims to recognition of Eastern Thrace and recognized Western Thrace as part of Bulgaria. The Ottomans withdrew their forces and by 25 October, and the area