Constituent units of the Russian Federation
Source (Wikipedia): Republics of Russia

The republics are one type of federal subject of the Russian Federation. 21 republics are internationally recognized as part of Russia; another is under its de facto control. The original republics were created as nation states for ethnic minorities. The indigenous ethnicity that gives its name to the republic is called the titular nationality. However, due to centuries of Russian migration, a titular nationality may not be a majority of its republic’s population. By 2017, the autonomous status of all republics was formally abolished, making the republics politically equivalent to the other federal subjects of Russia.