The Bosnia Vilayet (Serbo-Croatian: Bosanski vilajet/Vilajet Bosna) was a first-level administrative division (vilayet) of the Ottoman Empire, mostly comprising the territory of the present-day state of Bosnia and Herzegovina, with minor parts of modern Montenegro. It bordered Kosovo Vilayet to the south. Before the administrative reform in 1867, it was called the Bosnia Eyalet. In the late 19th century it reportedly had an area of 46,000 square kilometres (17,900 sq mi).
It effectively ceased to exist as an Ottoman province after the Austro-Hungarian campaign in Bosnia and Herzegovina in 1878, although it formally existed for thirty more years until 1908, despite being governed by Austria-Hungary. This excluded Old Herzegovina, which was ceded to the Principality of Montenegro in 1878. In 1908, during the Bosnian Crisis, Austria-Hungary formally annexed it into its own territory.
