<b>Abstract</b>— <p>The results of micromorphological, chemical, and microbiomorphic analyses of soils and earthen structures (kurgans) of the Mustaevo VI Yamnaya culture archaeological site dating back to the 3rd millennia BC and located in Cis-Ural steppe are discussed. Micromorphological analysis attests to close similarities in the earthen construction technologies of the two studied kurgans. Although radiocarbon dating attributes them to different stages of the Yamnaya culture, it is reasonable to assume that no more than 100 years elapsed between their construction dates. This determined the time scale of the detected changes in soil properties against a reconstructed stage of increased humidization and possible cooling of the climate in that period. Changes in the carbonate profile are recorded in the soil buried under the kurgan constructed later: the maximum of carbonates descended to a lower horizon. Initial signs of the mobility of Fe–clayey material are seen after the carbonate leaching. The content of carbonates in the upper part of the buried soil profile decreased, as well as pH_water values, loss on ignition, and the content of exchangeable Mg²⁺ and Na⁺, while magnetic susceptibility increased. Changes in the composition of the buried soil are consistent with those in the materials of kurgan structures, which independently confirm<Emphasis Type="Strikethrough">s</Emphasis> the accuracy of the reconstruction. The anthropogenic impact associated with the clearing of the floodplain forest before the kurgan construction manifested itself in an increased proportion of dry-steppe plants in the phytolith assemblage and a lower organic carbon content in the upper soil horizon buried under the later constructed kurgan.</p>