This paper summarizes the data on the Early Cretaceous palaeogeography of the Russian Platform (RP) in a context of the development of North-eastern Peritethys. One of the main features of the region is the constant mutual influence of the Tethyan and Boreal water masses through the system of straits. The latest Volgian to Barremian development of the RP basin was under the major influence of Boreal water mass (WM). It differs from the Aptian-Albian interval, which formed under major influence of Tethyan and Peritethyan WM. Zonal biostratigraphy reflects the type of marine biota related to the type of the WM. The WM movement interrupted by several episodes of exposition of the southern margin of the RP the Berriasian - Barremian or the almost the whole Platform in late Middle to late Aptian.