Stalin, as both head of the People's Commissariat of Nationalities and then of the whole Soviet Union, designed the borders of the ethnic republics and autonomous areas not to give each nationality its homeland but instead to reward and punish groups at his will. During his reign there were many harvests of ethnic blood through expulsions and mass killings. His death saw a curbing of ethnic killings; however, the collapse of the Soviet Union saw the incubated seeds of Stalin's ethnic violence emerge once more.
Before the fall of the Soviet Union, Georgia was comprised of Georgia-proper, the ethnic autonomous republic of Abkhaiza (for Abkhaz) and the autonomous oblast of South Ossetia (for Ossetians). The last Georgian Soviet leader and first Preisdent of Georgia, Zviad Gamsakhurdia, demanded a "Georgia for the Georgians" while pushing laws to strip ethnic minorities of their special regions. War broke out between Georgians against the Ossetians and Abkhaz who received military support from Russia. The conflict is currently frozen, the last spat was the 2008 Russia-Georgia War, which ended in another Georgian defeat and limited international recognition of de facto independent South Ossetia and Abkhazia.
As written about before in the Other Occupations piece, ethnic Armenians and Azeris went to war over an ethnic Armenian autonomous region in Azeribaijan. The war ended with Armenia occupying the western section of eastern Azerbaijan and the autonomous region now a de facto independent republic.
Republic of North Ossetia and Republic of Ingushetia, Russia
Muslim Ingush were forced into exile by Stalin because he believed they supported the Nazis during World War II. The Ingush, like many punished ethnic groups, were forced to relocate to Central Asia and Siberia in the mid-1940s. As the Soviet Union was collapsing many Ingush returned to their homeland and noticed it was smaller because much of the land was given to Christian Ossetians (who rival Belarusians in being the most Russian non-ethnic Russians). A conflict broke out in which Ossetians cleansed North Ossetia of many Ingush. Many Ingush from North Ossetia still live in refugee camps in Ingushetia today. The hatred of this loss has feed into the instablity in Ingushetia today.
The ethnic riots of 2010 are not the first mass ethnic killings in Kyrgyzstan. In 1990 in the city of Osh, one of the places where the 2010 ethnic riots is currently on-going, ethnic Uzbeks started to demand local cultural rights and autonomy. Ethnic Kyrgyz responded with riots that targetted Uzbek homes. Some Uzbeks from Soviet Uzbekistan in turn went to Osh to melee against the Kyrgyz rioters. Soviet Army troops were needed to quell the rioting and keep the peace.
Besides the four cases of mass ethnic killings above, there has been low level violence in Ukraine's Crimea where Crimean Tatars squatters are fighting ethnic Russian land owners over lands the Tatars lost because of one of Stalin's many ethnic exiles.
Stalin not only harvested ethnic violence during his reign but also laid the seeds for further violence with his expulsions and African-style border drawing. With Azeri-Armenian, Georgian-Ossetian-Abkhaz, and Krygyz-Uzbek tensions running high, expect Stalin's harvest to occur every so often.