The USSR, through its administrative structures, its education policies, and its way of 'resolving' the 'national question' served as the incubator for several national identities. Migration patterns within the USSR in some cases reinforced these national identities, either positively (e.g. Armenians concentrated in the Armenian SSR throughout the 20th century) or negatively (various outbreaks of inter-communal violence). Various 'nationalities' which hadn't existed before 1917 as imagined communities - especially in Central Asia - were created and given a literary language. In this work, the ethnographers and administrators of the Stalin era were building on a long-standing pre-revolutionary tradition of mapping the human geography of the empire. These new affinities, reinforced by literacy and education, came to replace religious or local affinities as markers of 'identity'. The Soviet internal passport (ID card) fixed everyone's 'nationality' as an administrative category. The Union bore the seeds of its own disintegration along ethnic and national lines, particularly once the supranational project of building a 'socialism' capable of outperforming capitalism had run out of steam.