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Rich ancient societies of central Asia developed on the basis of trade between East and West; their existence was dependent on natural resources that favoured agriculture. The branches of the Silk Road in central Asia clearly coincide with loess areas, where many settlements were erected based on the presence of fertile loess soil and water. The aim of the study was to analyse the environmental factors that led to the growth and decline of one of the most important Silk Road “loess towns,” ancient Panjikent, as an example of human and climatic impacts on landscape changes. The town, established in the fifth century, quickly became one of the most important cities of Sogdiana. Local loess material was used for the production of the sun-dried bricks. Rapid population growth led to deforestation and consequently increased the intensity of erosion rates and reductions in cultivation area. A period of drought near the end of the first millennium AD influenced the final abandonment of the ancient town and its relocation to the lower terrace of the Zarafshan River. A decline in natural and agricultural resources and subsequently climatic forces caused a decline in the number of cities in semiarid regions of central Asia.

We developed a 1108 yr chronology of tree-ring widths, based on 64 Himalayan pencil juniper (Juniperus semiglobosa Regel) trees, for the Pamir-Alay Mountains, central Asia. Dendroclimatological analysis demonstrates that precipitation has significant effects on tree growth in the semiarid mountainous area of northwestern Tajikistan located on the edge of the great midlatitude Karakum and Kyzylkum deserts. The highest level of linear correlation (r=0.67) is observed between tree growth and seasonalised winter (previous December–February) precipitation. Our studies also show that moisture (precipitation/Palmer Drought Severity Index) from the previous June to the current September was the dominant climatic factor accounting for interannual variations in tree-ring width, suggesting that this should be considered in climate reconstruction. Using the transfer function method, we reconstructed the region’s drought history over the period AD 908–2015. The results of this moisture reconstruction showed that the most recent millennium was characterised by series of dry and wet stages. The driest periods occurred before 1000, 1200–1250, and at the end of the eighteenth century and beginning of the nineteenth century. The wettest conditions existed in 1650–1700 and after 1990.

This study investigates the potential reconstruction of summer monsoon season streamflow variations in the middle reaches of the Yellow River from tree rings in the Qinling Mountains. The regional chronology is significantly positively correlated with the July–October streamflow of the middle Yellow River from 1919 to 1949, and the derived reconstruction explains 36.4% of the actual streamflow variance during this period. High streamflows occurred during 1644–1757, 1795–1806, 1818–1833, 1882–1900, 1909–1920 and 1933–1963. Low streamflows occurred during 1570–1643, 1758–1794, 1807–1817, 1834–1868, 1921–1932 and 1964–2012. High and low streamflow intervals also correspond well to the East Asian summer monsoon (EASM) intensity. Some negative correlations of our streamflow reconstruction with Indo-Pacific sea surface temperature (SST) also suggest the linkage of regional streamflow changes to the Asian summer monsoon circulation. Although climate change has some important effects on the variation in streamflow, anthropogenic activities are the primary factors mediating the flow cessation of the Yellow River, based on streamflow reconstruction.