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,
Northern Thrace Bulgaria occurred here: it was 45.2 °C at Sadovo in 1916. Important rivers are the Maritsa and its tributaries. Important cities include Plovdiv, Burgas, Stara Zagora, Sliven, Haskovo, Yambol, Pazardzhik, Asenovgrad, Kardzhali, Dimitrovgrad, Kazanlak and Smolyan. Northern Thrace has an area of 42,073 km². The Ottoman Turks created the autonomous province of Eastern Rumelia in northern Thrace in 1878. The region was annexed to the Principality of Bulgaria in 1885. Northern Thrace Northern Thrace or North Thrace (, ) (as opposed to Western Thrace and East Thrace to the south) constitutes the northern and the largest part of the historical