The Province of Bosnia or Pashaluk of Bosnia was a key Ottoman province, the westernmost one, mostly based on the territory of the present-day state of Bosnia and Herzegovina.
In the mid-17th century, at the peak of its size, the Bosnian pashaluk covered all of today's Bosnia and Herzegovina as well as most of Slavonia, Lika and Dalmatia in present-day Croatia. It encompassed eight sanjaks and 29 captaincies (military outposts):
However, the Ottoman wars in Europe continued and the province significantly decreased in territory during the same century. After the Treaty of Karlowitz, the province was down to four sanjaks (three of them diminished in size as well) and twelve captaincies. Before the Treaty of Passarowitz, another 28 military captaincies were formed, more than half of them along the frontier. This kind of intensive military administration corresponded to the Austrian Military Frontier on the other side of the same border.
In 1833, territory of Herzegovina region was separated from the Pashaluk of Bosnia and was turned into the separate Pashaluk of Herzegovina, whose vizier was Ali-paša Rizvanbegović. After his death in 1851, pashaluks of Bosnia and Herzegovina were merged into new entity known as Bosnia and Herzegovina.