The main attention of the article presented focuses on the connection between the development of archaeological cultures and environmental changes during the 9th -4th centuries BC (2700-2400 BP). Environmental changes around 2600 BP can be observed by the character of the radiocarbon calibration curve. The region under study is the Uyuk depression in the Tuva Republic which is the part of the Eurasian steppe belt. To reconstruct environmental changes pollen and geochemical analyses of the lake deposits from the Uyuk depression were used. The main feature that made this territory more attractive for settling, is the humidity that promoted nomadic economy. The chronology of the archaeological sites corresponds to a period with a complicated shape of the calibration curve, and a special approach (wiggle-matching dating) is required. The famous Scythian time monuments Arzhan-1 and Arzhan-2 are located in this region and the wiggle matching method was used to establish the time of their construction. The Arzhan-1 is the oldest among the Scythian time monuments of all Eurasia. The chronology of other Scythian time monuments located in the western and eastern neighbouring territories of Tuva is considered and compared.