At the turn of the Late Bronze and Early Iron Age in the steppe belt of Eurasia there were significant cultural transformations which probably had been connected with Rapid Climatic Cycles (RCC) in this time, around 3,2 ka calBP. The correlation of data obtained on the base of radiocarbon dating, paleoclimatic reconstructions and cultural and historical chronology for eastern and western zones of the Great Steppe allowed us to reconstruct these processes. In the Late Bronze period bearers of the Кarasuk culture spread in the steppe zone of the Southern Siberia from Central Kazakhstan to Mongolia and Northern Chine. Formation of the Late Bronze Age cultures Sabatinovka and Belozerka Active cultures took place during period of favorable environment. Then the bearers of the early Hallstattian Carpathian-Danubian cultures and the Cimmerian nomads appeared in the beginning of the Early Iron Age during the aridization episode. Since the middle of 9^th century BC expansion of the nomadic Scythian cultures within the whole steppe belt began because of wet climatic conditions.