Climatic factor is the key one in explaining changes in the system of population sustenance in Western Siberia and adjacent areas in the beginning of the 1st millennium B.C. Climatic fluctuations explain most of the changes in ethno-cultural processes and migration reasons in the Early Iron Age in the Ob- Irtysh interfluve area. In spite of a large number of works on the issue, the researchers do not agree on the degree of the landscape change as a result of climatic f luctuations and their inf luence on the economy of the population in the south of the Ob- Irtysh interfluve area in the Early Iron Age. The researchers are more unanimous about understanding mechanisms of changes in lives of the population in the beginning of the 1st millennium B.C. — the period with global climatic f luctuations (when prolonged aridization was followed by continuous humidity). The views on the period beginning in the second quarter of the 1st millennium B.C., with less distinct and prolonged climatic fluctuations, are more polarized. These require further study focusing, on the one hand, on the details of complicated changes of landscapes in the south of the Ob-Irtysh interf luve area in the 1st millennium B.C., and on the other hand, on developing models explaining climate inf luence on the herding economy in the steppe and forest-steppe areas of the region under study in Early Iron Age.