At the beginning of the 20th century, Bitlis Vilayet reportedly had an area of 11,522 square miles (29,840 km2), while the preliminary results of the first Ottoman census of 1885 (published in 1908) gave the population as 388,625.[4] The accuracy of the population figures ranges from "approximate" to "merely conjectural" depending on the region from which they were gathered.[4]
Bitlis and Muş were formerly included in the Eyalet of Erzurum. In 1875, they were detached and made a separate vilayet. The sanjak of Siirt was joined to the vilayet of Bitlis from Diyarbekir Vilayet in 1883–84.[5]
^Klein, Janet (3 August 2012). Jongerden, Joost; Verheij, Jelle (eds.). Social Relations in Ottoman Diyarbekir, 1870-1915. BRILL. p. 148. ISBN978-90-04-22518-3.