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Salmonella enterica (S. enterica) has infected humans for a long time, but its evolutionary history and geographic spread across Eurasia is still poorly understood. Here, we screened for pathogen DNA in 14 ancient individuals from the Bronze Age Quanergou cemetery (XBQ), Xinjiang, China. In 6 individuals we detected S. enterica. We reconstructed S. enterica genomes from those individuals, which form a previously undetected phylogenetic branch basal to Paratyphi C, Typhisuis and Choleraesuis–the so-called Para C lineage. Based on pseudogene frequency, our analysis suggests that the ancient S. enterica strains were not host adapted. One genome, however, harbors the Salmonella pathogenicity island 7 (SPI-7), which is thought to be involved in (para)typhoid disease in humans. This offers first evidence that SPI-7 was acquired prior to the emergence of human-adapted Paratyphi C around 1,000 years ago. Altogether, our results show that Salmonella enterica infected humans in Eastern Eurasia at least 3,000 years ago, and provide the first ancient DNA evidence for the spread of a pathogen along the Proto-Silk Road. Author summary: Recent studies that use DNA extracted from ancient human remains have shown that the bacterial pathogen Salmonella enterica has infected humans since prehistoric times. Expanding the knowledge about its geographic spread and genetic diversity we reconstructed six ancient Salmonella genomes from individuals excavated at the Bronze Age Quanergou cemetery in Xinjiang, China. Our analysis shows that this form of Salmonella was closely related to a type that today specifically infects humans and/or pigs. However, based on our genetic assessment we determined that our ancient strains were not host adapted yet. Furthermore, we could show that in the course of its evolution the bacterium acquired some important virulence factors earlier than previously thought. Interpreting our results within an archaeological context we suggest that in Bronze Age Eastern Eurasia the spread of this pathogen was likely promoted through trade networks referred to as the Proto-Silk Road. [ABSTRACT FROM AUTHOR]

• The aeolian soils along East Liao River and West liao River have have similar provenance and dynamic mechanism. • River-floodplains are the main source of this type of aeolian soil sediments. • Sediment component content of the profile is strongly influenced by changes in sedimentary environment. • Shrubland planting along rivers is an effective way to prevent regional desertification. There are many stabilized sand dunes along the East and West Liao rivers in the eastern side of the Horqin Sandy Land, and they pose a threat to the surrounding ecological environment and the livelihood of inhabitants once the ecological balance is destroyed. In order to explore the sediment provenance, dynamic mechanism and sedimentary environment of these aeolian soils, and to provide assistance in desertification prevention, two aeolian soil profiles and some topsoil samples were collected for grain size, loss on ignition and phytolith analysis in the East and West Liao River and Horqin Sandy Land, respectively. After end-member analysis of the grain size data, it is concluded that the aeolian soil profiles along the East Liao River and West Liao River have similar provenance and dynamic mechanism. The river-floodplain contributes most to the formation of these aeolian soils and then the Horqin Sandy Land and the interior of Eurasia, and the sediments were transported to the river banks by creep, saltation and suspension in different proportions. The Ic index reconstructed by phytolith, combined with the surrounding sedimentary environmental reconstruction records, the climate experienced several warm-wet and cold-dry periods from 7,720 to 400 cal yr BP, and it significantly influenced the percentages of each component of the profile in each period. The research suggests that planting drought-tolerant shrub plants along the rivers to form shrub belts can effectively prevent the transport of aeolian soils along the rivers, and planting trees and grass on the aeolian soils to increase the vegetation cover, combined with publicity and management, is viable for desertification prevention. [ABSTRACT FROM AUTHOR]