In the 20th, the divide-and-rule tactics of the Stalin era involved weakening resistance by splitting related groups and joining unrelated ones in shared administrative units.

BBC: Karachay-Cherkessia profile

Its roots date back to the Stalin era, when the government built a 525-mile pipeline to bring gas from Saratov in the south to Moscow.

FORBES: Energy Tsar

Though he is ethnically Chechen, Anzor Tsarnaev grew up in the former Soviet republic of Kyrgyzstan because his parents were deported there in the Stalin era alongside many other ethnic Chechens.

WSJ: Russia Distances Itself From Chechen Brothers