Oblast

An oblast (, ; plural oblasts, oblasti, or rarely oblasty; Russian and область; вобласць; област; облыс; облус) is a type of administrative division in Bulgaria and several post-Soviet states, including Belarus, Russia and Ukraine. Historically, it was used in the Russian Empire and the Soviet Union. The term oblast is often translated into English as region or province. In some countries, oblasts are also known by cognates of the Russian term.

Etymology
The English term oblast is borrowed from область, where it is inherited from Old East Slavic, in turn borrowed from область, formed from the prefix oб- (cognate with Classical ob and ἐπί, ἔπι) and власть. In Old East Slavic it was used alongside оболость, equivalent of об- and волость, cognate with English wield; see volost.

Russian Empire
In the Russian Empire, oblasts were considered to be administrative units and were included as parts of Governorates General or krais. The majority of then-existing oblasts were on the periphery of the country (e.g. Kars Oblast or Transcaspian Oblast) or covered the areas where Cossacks lived.

Soviet Union
In the Soviet Union, oblasts were one of the types of administrative divisions of the union republics. As any administrative units of this level, oblasts were composed of districts (raions) and cities/towns directly under oblasts' jurisdiction. Some oblasts also included autonomous entities called autonomous okrugs. Because of the Soviet Union electrification program under the GOELRO plan, Ivan Alexandrov, as director of the Regionalisation Committee of Gosplan, divided the Soviet Union into thirteen European and eight Asiatic oblasts, using rational economic planning rather than "the vestiges of lost sovereign rights".

The names of oblasts did not usually correspond to the names of the respective historical regions, as they were created as purely administrative units. With a few exceptions, Soviet oblasts were named after their administrative centers.

Yugoslavia
In 1922, the Kingdom of Serbs, Croats and Slovenes was divided into 33 administrative divisions also called oblasts. In 1929, oblasts were replaced with larger administrative units known as banovinas.

During the Yugoslav Wars, several Serb Autonomous Oblasts were formed in Bosnia and Herzegovina and Croatia. These oblasts were later merged into the Republic of Serbian Krajina and the Republika Srpska.

Bulgaria
Since 1999, Bulgaria has been divided into 28 oblasts, usually translated as "provinces". Before, the country was divided into just nine units, also called oblasts.

Post-Soviet states
Viloyat and welaýat are derived from the Turkish language term vilayet, itself derived from the Arabic language term wilāya (ولاية).