oblast [Rus.,=region], administrative and territorial division in Russia, Ukraine, Belarus, and the former USSR. In the USSR, oblasts in which the majority of the population was of a nationality different from that of the constituent republic in which they were included generally enjoyed autonomous status. There is only one surviving autonomous oblast in Russia; the others became republics. The boundaries of oblasts are usually based on economic and administrative considerations; as a result, oblasts vary considerably in size and population.

Oirat Autonomous Oblast or Oirot Autonomous Oblast: see Altai Republic, Russia.