This paper is focused on the discussion of the exact age, and environmental setting of the ‘Khvalynian’ Transgression of the Caspian Sea with the use of novel radiometric, isotopic evidence and GIS-linked modelling. Based on this evidence the Khvalynian transgression is viewed as coeval with the warm Late Glacial episodes in the higher latitudes, reaching its peak at 13.6 - 11.8 ka. During that period the Caspian Sea was connected with the Caspian Sea via the ‘Manych-Kerch-Spillway’ north of the Caucasus Mountains. We also suggest a younger age for Mousterian sites in the Caspian basin, which are usually associated with the populations of Neanderthal humans. The initial emergence of Mousterian industries in this area was broadly contemporaneous with MOI 3 that included the LGM (25-18 ka). Their expansion was largely coeval with the Khvalynian transgression.