The article discusses a geological position of the U/Th data from the buried peat bogs in the down-stream and mid-channel of the Ob, the lower course of the Irtysh and the North Angara basin, together with the accompanied ¹⁴C-data and paleobotanic materials from the layers encompassing, overlapping and underlying the sampling places to that U/Th and ¹⁴C-data. It is found out that stratotypes of subhorizons of the Kargino horizon, namely, those of Shuryshkar, Zolotomys, and Kiryas being of the Kazantsevo Age for the first two ones, and the age of the early (“Siberian Brehrup”) interstadial of the Zyriansk Glaciation for the last stratotype. The Zyriansk Age being also associated with one of the key sections of the Lokhpodgorian subhorizon confined to the Kargino horizon. The data allow to outline succession of the paleoclimatic events within the limits of the Kazantsevo interglaciation, correlating these with the events reflected in the ice core of Greenland. In the north of West Siberia subject to the identification being 5e5, 5e1 paleoclimatic events, while subject to the outline – 5e2, 5e3 and 5e4 events. As to the main optimum, it was 5e5 event. 5e1 optimum being of the double character. It is found out that the Kazantsevo interglaciation in the north of West Siberian lowland started several thousand years earlier than MIS-5 stage. Shifting of the vegetation zones in the west of West Siberian lowland to the north during the main optimum of the Kazantsevo time in the area of the polar circle reached 700km, while around 60°NL and further to the south  – only 300-400km. During pessimums of the Kazantsevo time, shifting of the vegetation zones to the south was less than 100km.

Key words: U/Th data, peat bogs of the lower and middle parts of the Ob, Irtysh, and Angara basin, stratotypes of the Kargino horizon, paleoclimate within the Kazantsevo interglaciation.

The article presents the results of an integrated archaeological and paleogeographical investigation of Vyngayakha 7 medieval settlement (the Pur river basin). It is stated that the advancement of the Vozhlaj communities to the north in the IX-XII centuries could be, among others, explained by a migration response to the change of natural conditions. The started warming up (the minor climatic optimum of Holocene) favourably told on the habitation conditions in the north taiga zone, making these territories attractive for the bearers of the Vozhlaj culture.

Key words: West Siberia, Holocene, medieval archaeology, the Vozhlaj culture, climatic reconstruction, migration processes.