Abstract. We have carried out power spectrum, time-spectrum and bispectrum analyses of the long-term series of the radiocarbon concentrations deduced from measurements of the radiocarbon content in tree rings for the last 8000 years. Classical harmonic analysis of this time series shows a number of periods: 2400, 940, 710, 570, 500, 420, 360, 230, 210 and 190 years. A principle feature of the time series is the long period of ∼ 2400 years, which is well known. The lines with periods of 710, 420 and 210 years are found to be the primary secular components of power spectrum. The complicated structure of the observed power spectrum is the result of ∼ 2400-year modulation of primary secular components. The modulation induces the appearance of two side lines for every primary one, namely lines with periods of 940 and 570 years, of 500 and 360 years, and 230 and 190 years. The bispectral analysis shows that the parameters of carbon exchange system varied with the ∼ 2400-year period during the last 8000 years. Variations of these parameters appear to be a climate effect on the rate of transfer of 14 C between the atmosphere and the the ocean.

In south-central Siberia archaeological evidence suggests an acceleration of cultural development and an increase in the density of nomadic populations around 850 BC. We hypothesize a relationship with an abrupt climatic shift towards increased humidity caused by a decline of solar activity. Areas that initially may have been hostile semi-deserts changed into attractive steppe landscapes with a high biomass production and high carrying capacity. Newly available steppe areas could be invaded by herbivores, making them attractive for nomadic tribes. The central Asian horse-riding Scythian culture expanded, and an increased population density was a stimulus for westward migration towards southeastern Europe.

ABSTRACT. The paper is compares the chronology of the monuments of the Scythian epoch located in the east and west of the Eurasian steppe zone on the basis of both archaeological and radiocarbon data. The lists of 14 C dates for the monuments located in different parts of Eurasia are presented according to the periods of their existence. Generally, the 14 C dates are confirmed the archaeological point of view and allow us to compare the chronological position of the European and Asian Scythian monuments on the united 14 C time scale.

This paper focuses on the chronological study of 2 Scythian period monuments that are the key to the chronology of the entire Eurasian Scythian culture. These are the unique monuments of Arzhan-1 and Arzhan-2 in Central Asia (Tuva Republic). The dating of both these monuments began immediately after their discovery, but discussion about their chronological position is still current. Both monuments contained considerable wooden material from their construction suitable for dendrochronology and radiocarbon dating. The first results for the Arzhan-1 barrow were obtained by wiggle-matching in 2004–2005, while the Arzhan-2 barrow was first dated in 2003. It is now possible to compare the chronological position of these barrows using the same methods. As postulated earlier, Arzhan-1 is the oldest Scythian period monument and is dated to the boundary of the 8–9th centuries BC. The position of the Arzhan-2 monument stretches to the middle of the 7th century BC. δ13C values for annual tree rings in logs from both barrows were also determined to gain a better understanding of the climatic conditions at the time of barrow construction.