Abstract <p>Multidimensional global changes are projected onto Russia and its regions, calling attention to the problems of spatial development. The purpose of this article is to form systemic ideas about Southern Russia as one of the key and most dynamic macroregions, prolonged and current problems of implementing the “southern vector” of the spatial socioeconomic dynamics of the country, and the strategic priorities of the regional genesis of Southern Russia and its new (“broader”) formats. Attention is focused, in particular, on the long-term trend of the “flow” of the population to Southern Russia and the transformation of its ethnic structure. The “wavelike” dynamics of population growth in Southern Russian macroregion has been identified; it is related to its position in the center–periphery system of the country, as well as ethnodemographic and geopolitical circumstances. This article shows the sociogeographical specificity of Southern Russia that developed in the post-Soviet period and is transforming in the “post-Crimean” conditions (polyethnicity, coastalness, near-border location, comparative agroclimatic and recreational “southerness,” stability of the residential structure, etc.), as well as its functionality on a national scale (agricultural–industrial, residential–recreational, transport–logistics, and military–geostrategic). The current megatrends in the natural–economic and ethnocultural spheres inherent in the Southern Russian macroregion are characterized. It is emphasized that the deepening stratification of the Southern Russian space (including under the influence of ethnodemographic processes at the regional and municipal levels) and its development as a whole according to the polycentric model are combined with the accelerated formation (due to changes in geopolitics, transport infrastructure, and the economic sphere) of interregional and transboundary aquaterritorial integrity: Greater Southern Russia.</p>