Several metallogenic belts were earlier recognized by S.S. Smirnov in Transbaikalia rich in polymetallic endogenous mineralization. Despite the continuing geological and geophysical studies in the region, the borders of these belts are still hotly debatable. The results of geophysical and seismic tomographic studies in East Asia (where a stagnant oceanic slab was discovered in the mantle transition zone) and the location of highly productive ore-magmatic systems in the regional Earth’s crust testify to the spatial coincidence of the projection of the frontal part of the slab with the Dalainor–Gazimur-Olekma mineragenic zone. Most of large and superlarge ore nodes and fields with Au, Mo, U, Pb–Zn, Cu, and fluorite mineralization are localized in this zone. The difficult problem of mineragenic regionalization here can be solved by proving the probable influence of mantle fluid flows formed near the frontal part of the slab on the formation of highly productive ore-magmatic systems of the above zone oriented orthogonally to the earlier recognized belts. The experience gained during the comprehensive studies of minerageny both in eastern Transbaikalia and in other ore-bearing provinces can be used to choose ore-promising areas for prediction, prospecting, and assessment works.