Central Asia

The Soviets didn't use the Tsars's administrative districts, and instead created linguistic areas. They did this consciously.

Since Soviet Disunion, there has been relative stability in the Central Asian countries of Kazakhstan, Turkmenistan, Uzbekistan, Kirghizistan and Tajikistan. Meanwhile, other countries in the region, especially Afghanistan and Pakistan, but including Chinese Xinjiang and Iran, have not had as much luck in the same time frame.