Central Asia
Russia had conquered Central Asia in the 19th century by annexing the formerly independent Khanates of Kokand and Khiva and the Emirate of Bukhara.
After the Communists took power in 1917 Russian Revolution and created the Soviet Union it was decided to divide Central Asia into ethnically-based republics in a process known as National Territorial Delimitation (or NTD).
This was in line with 2 things
Communist theory that nationalism was a necessary step on th