Exploring the history of cultural exchange in prehistoric Eurasia from the perspectives of crop diffusion and consumption

Identifying the origin of moisture is a key process in revealing the formation mechanisms of precipitation, but the moisture sources for central Asia have not been well documented in previous studies. In this work, we employ the Lagrangian model FLEXPART over 2011–19 to address this question. Multiple observational products indicate that the times of dry and wet seasons are opposite for western and eastern central Asia bounded by 75°E. The wet season is November–April (NDJFMA) for western central Asia but May–October (MJJASO) for eastern central Asia, while the opposite is true for the dry season. The main moisture source regions for western central Asia are local regions (with a contribution of 49.11%), western Eurasia (21.47%), and western Asia (11.37%) during MJJASO and local regions (33.92%), western Asia (27.50%), and western Eurasia (17.60%) during NDJFMA. For eastern central Asia, moisture mainly originates from local regions (52.38%), western central Asia (25.22%), and northern Eurasia (9.26%) during MJJASO and western central Asia (30.86%), local regions (30.82%), western Asia (10.31%), and western Eurasia (10.26%) during NDJFMA. The differences in moisture sources between dry and wet seasons mainly occur in local regions and western Asia for western central Asia but in local regions for eastern central Asia. The moisture from northern Eurasia, western Eurasia, and western central Asia is transported into target regions by the westerly and southwesterly winds that are associated with a deep low trough over central Asia. Moisture is transported from western Asia by the anticyclone occurs over North Africa and western Asia in the lower and middle troposphere.

With the decline of Tang Empire in the 8th century, the unitary postal system connecting China proper with the Hexi corridor and eastern Central Asia ceased to function. Buddhist and Christian communities took up the role with their networks that transcended the boundaries of states. Buddhist and Christian monks were entrusted with diplomatic and commercial duties as official envoys and sent to distant states via their own religious networks. Monasteries along the main routes filled the gaps left by the former relay posts, especially in relatively isolated areas where no civilian conurbations existed. Akin to the prevalent Buddhism, the Christian network also extended to most regions in east Central Asia and Gansu by the 9–10 cc. This was centrally organised under the leadership of the metropolitan in Merv, resulting in highly efficient communications within these regions, as well as with western Central Asia and northern Asia.

With the decline of Tang Empire in the 8th century, the unitary postal system connecting China proper with the Hexi corridor and eastern Central Asia ceased to function. Buddhist and Christian communities took up the role with their networks that transcended the boundaries of states. Buddhist and Christian monks were entrusted with diplomatic and commercial duties as official envoys and sent to distant states via their own religious networks. Monasteries along the main routes filled the gaps left by the former relay posts, especially in relatively isolated areas where no civilian conurbations existed. Akin to the prevalent Buddhism, the Christian network also extended to most regions in east Central Asia and Gansu by the 9–10 cc. This was centrally organised under the leadership of the metropolitan in Merv, resulting in highly efficient communications within these regions, as well as with western Central Asia and northern Asia.

Spatial reconstructions of drought for central High Asia based on a tree-ring network are presented. Drought patterns for central High Asia are classified into western and eastern modes of variability. Tree-ring based reconstructions of the Palmer drought severity index (PDSI) are presented for both the western central High Asia drought mode (1587–2005), and for the eastern central High Asia mode (1660–2005). Both reconstructions, generated using a principal component regression method, show an increased variability in recent decades. The wettest epoch for both reconstructions occurred from the 1940s to the 1950s. The most extreme reconstructed drought for western central High Asia was from the 1640s to the 1650s, coinciding with the collapse of the Chinese Ming Dynasty. The eastern central High Asia reconstruction has shown a distinct tendency towards drier conditions since the 1980s. Our spatial reconstructions agree well with previous reconstructions that fall within each mode, while there is no significant correlation between the two spatial reconstructions.

The topography of the Tianshan Mountains and the Pamir Plateau strongly shapes the seasonality of precipitation in Central Asia (CA): cold-season (October-April) precipitation dominates western CA and warm-season (May-September) precipitation dominates eastern CA. The precipitation/moisture patterns between western and eastern CA are completely opposite at seasonal, decadal and centennial scale. However, the pattern contrasts for millennial or longer time scales remain unknown. In this study, we investigated the precipitation variations in western CA, as recorded in a 6.5-m loess section in southern Kazakhstan, which has accumulated since ~14.4 ka. According to the robust relationship between the surface soil organic matter δ13C and the climatic parameters, the δ13C signature is here considered as a precipitation proxy. The record reveals an overall decreasing precipitation before ~6.0 ka followed by an increasing trend afterward, being consistent with the previously reported precipitation records in western CA. The late-deglaciation precipitation in western CA is in phase with that in eastern CA at millennial scales, which are both driven by the North Atlantic Oscillation (NAO) and the Siberian High.

Late Neolithic Plant Remains from Northern China: Preliminary Results from Liangchengzhen, Shandong

The origin, development and expansion of prehistoric agriculture in East Asia have been widely investigated over the past two decades using archaeobotanical analysis from excavated Neolithic and Bronze Age sites. Research on prehistoric agriculture has predominantly focused in the valleys of the Yellow River and the Yangtze River. Agricultural development during the Neolithic and Bronze Age periods in the Yunnan-Guizhou Plateau of southwest China, an important passageway for human migration into Southeast Asia, still remains unclear. In this paper, based on macrofossil and microfossil analysis and radiocarbon dating at the Shilinggang site, we investigate plant subsistence strategies in the Nujiang River valley during the Bronze Age period. Combined with previous archaeobotanical studies in the Yunnan-Guizhou Plateau, we explore agricultural development processes in this area during the Neolithic and Bronze Age. Our results indicate that rice and foxtail millet were cultivated in Shilinggang around 2500 cal a BP. Three phases of prehistoric agricultural development in the Yunnan-Guizhou Plateau can be identified: rice cultivation from 4800–3900 cal a BP, mixed rice and millet crop (foxtail millet and broomcorn millet) cultivation from 3900–3400 cal a BP, and mixed rice, millet crop and wheat cultivation from 3400–2300 cal a BP. The development of agriculture in the Yunnan-Guizhou Plateau during the Neolithic and Bronze Age periods was primarily promoted by prehistoric agriculture expansion across Eurasia, agricultural expansion which was also affected by the topographic and hydrological characteristics of the area.

Many cases of intercontinental disjunct distributions of seed plants have been investigated, however few have concerned the continents of Eurasia (mainly Central Asia), Africa, and Australia, especially the xerophytic lineages are lacking. Nitraria (Nitrariaceae) is just one of these xerophytic lineages. Previous Nitraria studies have hypothesized either Africa as the ancient center, with dispersals to Australia and Eurasia, or alternatively Central Asia, due to a concentration of endemism and diversity there. Our findings show eastern Central Asia, i.e. the eastern Tethys, to be the correct place of origin. Dispersal westward to Africa occurred during the late Oligocene to Pliocene, whereas dispersal to Australia from western Central Asia was young since Pliocene 2.61 Ma. Two related tetraploids are indicated to have diversified in eastern Central Asia at approximately 5.89 Ma, while the Australian tetraploid N. billardieri, is an independently derived, recent dispersal from western Central Asia.

Hybridization-differentiation is a major pathway of speciation and the active force of plant evolution, including homoploid speciation without change of chromosome numbers. Effective isolation between parental species and their hybrid derivatives plays an essential role in homoploid speciation for stabilizing a newly formed species. Studies of isolation mechanisms will facilitate our understanding of the speciation process. The genus Elymus of Triticeae ( Poaceae) includes ca. 150 polyploid species with different genomes, viz. the StH, St Y , StHY, StPY, and StWY from different origins, providing an ideal group for studying mechanisms of polyploid and homoploid speciation. There are about 30 tetraploid species containing the StY genomes distributed in temperate Asia and the eastern margin of Europe. In order to study genomic relationships of the StY Elymus species, samples representing 26 species collected from Western through Eastern Asia were extensively hybridized with each other. Meiotic pairing at metaphase-I of the intra- and interspecific hybrids was analyzed, which revealed a significant differentiation pattern in hornology of the StY genomes among Elymus species studied. Species from the same regions, e. g. within eastern or western Asia, shared the StY genomes with a relatively low level of differentiation, but species from different regions, e. g. between eastern and western Asia, shared substantially differentiated StY genomes. Species from Central Asia contained intermediately differentiated StY genomes compared with those from western and eastern Asia. The discovery of geographical differentiation of the StY genomes in tetraploid Elymus species has significance for study of evolutionary processes and mechanisms of homoploid speciation in Elymus. In addition to other well-recognized factors responsible for the isolation between parental species and their hybrid derivatives during the hybridization-differentiation process ( such as temporal, spatial, genie , and ecological isolation) , the authors believe that meiotic irregularity caused by genomic differentiation between species also provides an important mechanism for homoploid speciation.

Central Asia (CA) is one of the world's most significant arid regions, which is markedly impacted by global warming. A better understanding of the dynamical processes governing its Holocene climate variability is critical for a better understanding of possible future impacts of climate change in the region. To date, most of the existing CA paleoclimate records are from the summer precipitation-dominated eastern CA (ECA), with few records from the winter precipitation-dominated western CA (WCA). Here, we present a precisely dated (~6‰) and highly resolved (<4-y) record of hydroclimatic variations from the WCA covering the period between 7,774 and 656 y BP. Utilizing multiple proxies (δ18O, δ13C, and Sr/Ca) derived from a stalagmite from the Fergana Valley, Kyrgyzstan, we reveal a long-term drying trend in WCA, which is in contrast with the wetting trend in ECA. We propose that different responses of winter and summer westerly jets to seasonal solar insolation over the past 8,000 y may have resulted in an antiphased precipitation relationship between the WCA and ECA. Our data contain dominant quasiperiodicities of 1,400, 50 to 70, and 20 to 30 y, indicating close connections between the WCA climate and the North Atlantic. We further identified a series of droughts and pluvials on centennial-to-decadal timescales, which may have influenced regional societies and trans-Eurasian culture exchanges during historical and prehistorical times.

El Niño/Southern Oscillation (ENSO) events produce anomalous oceanographic and atmospheric conditions in regions far from the equatorial central-eastern Pacific, which modulate the atmospheric and surface processes that influence the dust emission, transport, and deposition in many places on Earth. In this study, we examined the MERRA-2 dust column mass density data in five subregions of the “dust belt”: eastern and western Arabian Peninsula, western and eastern Central Asia, and North Africa-Sahara during 1980–2021. We discovered that, while there is a common dust season from April to July, the specific dust seasons in these subregions are different with the peaks of dust activity occurring at different times of the year. In the meantime, the modulating effects of ENSO also peak at different times within the respective dust seasons. For example, ENSO has a persistent effect on dust activity during April-August in the eastern Arabian Peninsula, while its influence in eastern Central Asia lasts from February to November. For different well-recognized factors of dust activities, such as precipitation/humidity, wind, vegetation, and soil moisture, their responses to ENSO are also different in these subregions. For precipitation, humidity, and soil moisture, their responses to ENSO are mostly positive in winter and spring/early summer months during El Niño years, while mean daily maximum wind responded positively in spring, but it did so negatively in summer. During the three months when the ENSO’s effects were strongest, these factors could explain 25.1–58.6% of the variance in the dust column mass density in combination with the ENSO’s modulation effects. However, the highest model-explained variance was obtained for the North Africa–Sahara subregion where the intensity of dust activity was not statistically correlated with ENSO.

Dust aerosols are a major component of atmospheric aerosols, impacting climate systems and human health. In Asia, dust storms pose significant threats to air quality and public health, particularly in China, Korea, and Japan. Additionally, dust deposition in China's coastal regions supplies trace elements and nutrients that influence microbial communities, affecting marine productivity. Over the Tibetan Plateau, dust reduces snow and ice albedo, accelerating glacial melting. Given these impacts, understanding the sources and contributions of dust aerosols is crucial. Therefore, we focused on typical regions in Asia&amp;#8212;North China, Southeast China, the Korea-Japan region, the East China Sea, and the Tibetan Plateau&amp;#8212;and selected four primary dust source regions: Eastern Central Asia (ECA), Western Central Asia (WCA), West Asia-South Asia (WA-SA), and North Africa-Middle East (NA-ME).Previous studies on tracing the sources of airborne dust have largely relied on back-trajectory analysis. However, simply using the number of air mass trajectories passing over a desert to determine dust sources can lead to an overestimation of the relative contribution from source regions. This method, which did not consider the dust load in the transported air masses, resulted in an inaccurate evaluation of the desert-source contribution to the study regions. To address this issue, we present a novel algorithm for source-tracing of airborne dust (STAD), which incorporates satellite and reanalysis-based estimates to more precisely track dust activity and provide a more accurate quantification of source contributions. Overall, ECA emerges as the dominant source of dust affecting East Asia. In regions such as North China and the Korea-Japan area, ECA accounts for 60%-70% of dust transport, with WCA contributing around 20%. In Southeast China and the East China Sea, ECA still plays a major role, contributing 40%-50% of the dust. The Tibetan Plateau, as a dust transit hub in the Northern Hemisphere, has a complex dust source composition. The airborne dust at high altitudes over the Tibetan Plateau shows considerable spatial variation and primarily comes from desert clusters in ECA, WCA, and WA-SA. The Karakum, Taklimakan, and Thar deserts are significant sources of high-altitude airborne dust in the northwest, northeast, and southwest regions of the TP, with average mass loadings (mg m&amp;#8315;&amp;#178;) contributing rates of 42.2% (32.9), 49.6% (48.3), and 16.4% (32.1), respectively.This research lays a solid foundation for future studies on the role of dust aerosols in the Asian climate system, including their impacts on water cycles, weather patterns, and long-term environmental changes, providing crucial insights for developing effective mitigation strategies.

The Karakoram-Himalayan region is the cradle from where ancient Indian culture including Buddhism spread to different directions in Central Asia, East Asia and South East Asia. Gilgit, Chilas, Chitral, Baltistan, Ladakh, Zanskar and other frontier areas have been important mileposts on the famous Silk Route. Buddhist savants from India contributed to the spread of Buddhism in Central Asia and East Asia. One of the eminent scholars was Kumarajiva (344-413 AD) who broke political, geographical, cultural and linguistic barriers for propagation of Buddhism. Hieun Tsiang mentions four important centres of Buddhism in Central Asia - Shan-shan (Kroraina), Khotan, Kucha and Turfan. Kashmir played an important role in introducing Buddhism to Khotan, which in turn played a key role in the transmission of Buddhism to China. Several important places on the Silk Route system such as Kucha, Balkh, Bamiyan, Khotan, Kashgar etc. developed into important centres of Buddhism when parts of Central Asia and north-western India were integrated into a single kingdom under the Kushans.)

Coniferous forests cover the mountains in many parts of Central Asia and provide large potentials for dendroclimatic studies of past climate variability. However, to date, only a few tree-ring based climate reconstructions exist from this region. Here, we present a regional tree-ring chronology from the moisture-sensitive Zeravshan juniper (Juniperus seravschanica Kom.) from the Kuramin Range (Tajikistan) in western Central Asia, which is used to reveal past summer drought variability from 1650 to 2015 Common Era (CE). The chronology accounts for 40.5% of the variance of the June–July self-calibrating Palmer Drought Severity Index (scPDSI) during the instrumental period (1901 to 2012). Seven dry periods, including 1659–1696, 1705–1722, 1731–1741, 1758–1790, 1800–1842, 1860–1875, and 1931–1987, and five wet periods, including 1742–1752, 1843–1859, 1876–1913, 1921–1930, and 1988–2015, were identified. Good agreements between drought records from western and eastern Central Asia suggest that the PDSI records retain common drought signals and capture the regional dry/wet periods of Central Asia. Moreover, the spectral analysis indicates the existence of centennial (128 years), decadal (24.3 and 11.4 years), and interannual (8.0, 3.6, 2.9, and 2.0 years) cycles, which may be linked with climate forces, such as solar activity and El Niño-Southern Oscillation (ENSO). The analysis between the scPDSI reconstruction and large-scale atmospheric circulations during the reconstructed extreme dry and wet years can provide information about the linkages of extremes in our scPDSI record with the large-scale ocean–atmosphere–land circulation systems.

Ecosystem water use efficiency (WUE) and ecosystem photosynthetic efficiency (EPE) are key indicators in studies of the carbon–water cycle in terrestrial ecosystems. Analyses of WUE and EPE can enhance our understanding of the relationship between ecosystem light use efficiency and WUE. Although several studies of individual indexes (i.e., either WUE or EPE) have been conducted, analyses of variation in both WUE and EPE, as well as their relationships, have rarely been conducted. Here, we analyzed spatial and temporal variation in WUE and EPE in Central Asia. Specifically, time trend analysis was conducted to characterize temporal and spatial changes in WUE and EPE in Central Asia from 2001 to 2020 at different altitudes and latitudes. Pearson correlation analysis was used to characterize the effects of precipitation and temperature on WUE and EPE. WUE decreased and EPE increased in Central Asia over the 20-year study period; this might have been due to interannual variations in precipitation and temperature. WUE was highest in August, and EPE was highest in June and July. Substantial spatial heterogeneity in WUE and EPE was observed; WUE was highly variable in Central Asia as well as in western and southern Central Asia. Major changes in EPE were observed in northern, eastern, and southern Central Asia. We also found that both WUE and EPE decreased with the increase in altitude. WUE was positively correlated with temperature and negatively correlated with precipitation, whereas EPE was positively correlated with both temperature and precipitation. The increase in photosynthetic efficiency might be one of the main factors contributing to increases in ecosystem productivity in arid environments. The temporal and spatial variation in WUE and EPE observed in our study will aid ecosystem research, providing a reliable theoretical basis for ecosystem research in areas with scarce large-scale data, integrated water resources management, and ecosystem restoration efforts. Our findings also enhance our understanding of the terrestrial carbon–water cycle and have implications for predicting ecosystem responses to climate change. The results of this study provide insights that will aid studies of the terrestrial carbon–water cycle under the background of climate change. It is of great significance to further study the carbon water cycle in the future.