The demographic development and ethnic composition of the Russian Empire regions significantly determined the problem background of the prerevolutionary years, the social movement character and political slogans. The article studies population size and structure in the Steppe Region and Turkestan on the eve of the revolutions in 1917 on the basis of the archival and statistical sources and gives the estimate of the social and political consequences of the ethnodemographical changes. In the beginning of the XX century the steppe area of the Russian Empire was characterized by the population growth due to the natural increase and migrants’ inflow and by the increase of the non-native population proportion in the population structure. The territories left by the migrants were situated predominantly in the European part of Russia which determined the ethnic and religious composition of migrants. In the majority of the territories the Slavic population proportion increased greatly compared to the census data of 1897. Local migratory crises and inability of authorities to react to them significantly aggravated both the land question, and other socially significant problems. Ethnodemographical changes caused by the migration politics promoted the escalation of the social contradictions and as a result the increase of conflicts in the relationship of the different local communities.