By 4000 BP, trans-Eurasian agricultural exchanges increased across the Hexi Corridor. However, the nature and timing of many early prehistoric agricultural exchanges remain unclear. We present systematically collected archaeobotanical data from the ancient Haizang site (3899–3601 cal a BP) within the Hexi Corridor. Adding to previous archaeobotanical studies of the Hexi Corridor, we find that agricultural production transformed from purely millet-based agriculture during the Machang Period (4300–4000) to predominantly millet-based agriculture increasingly supplemented with wheat and barley during the Xichengyi and Qijia periods (4000–3600 BP). These transformations are likely due to adaption to a cooler and drier climate through cultural exchange. A warm and humid climate during 4300–4000 BP likely promoted millet agriculture, Machang cultural expansion westward, and occupation across the Hexi corridor. However, after the “4.2 ka BP cold event” people adopted wheat and barley from the West to make up for declining millet agricultural productivity. This adoption began first with the Xichengyi culture, and soon spread further eastward within the Hexi Corridor to the Qijia culture.

Archaeobotanical studies have largely illuminated spatiotemporal differences in agricultural development across the Loess Plateau. However, the particularities of local agricultural development have not been adequately studied for complex geographical, environmental, and prehistoric contexts. Here, new archaeobotanical data and radiocarbon dating results from 27 Neolithic and Bronze Age sites in Baoji are reported. Combining these data with published archaeobotanical datasets, this study explores shifts (and underlying driving factors) in cropping patterns from the late Neolithic to Bronze Age on the southern Loess Plateau (SLP). Regional geographic, environmental, and climatic factors produced mixed millet-rice agricultural systems in the Guanzhong Plain (GZP) and western Henan Province (WHN) and foxtail and broomcorn millet dry-farming systems in the Upper Weihe River (UWR) from 5800–4500 cal BP. Wheat and barley were added to the agricultural systems of the UWR as auxiliary crops after ~4000 cal BP, while cropping patterns remained largely unchanged in GZP and WHN from 4500–3500 cal BP. Cultural exchanges and technological innovations may have influenced the formation of different agricultural patterns across the three regions (i.e., GZP, WHN, and UWR) from 4500–3500 cal BP. From 3500–2200 cal BP, wheat and barley became increasingly important crops on the SLP, although their importance varied spatially, and rice was rarely cultivated. Spatiotemporal variation in cropping patterns was driven by altered survival pressures associated with climate deterioration and population growth from 3500–2200 cal BP. This process was reinforced by internal social developments, as well as interactions with close northern neighbors, in the Shang-Zhou period.

Stable isotopic analyses of the remains of plants that have been unearthed from archaeological sites are often featured as key indicators of crop cultivation and the living environment. However, systematic archaeobotanical studies have not been applied widely in Chinese historical sites, especially in those from the Tang dynasty. This paper aims to use carbon and nitrogen isotopic analyses to reveal the potential influence of water and fertilizer conditions on the size of millet chaffs that were excavated from the Chashancun cemetery. To achieve this, >3600 uncharred broomcorn and foxtail millet chaff remains were measured. Furthermore, 30 broomcorn millet samples and 30 foxtail millet samples were selected to analyze the carbon and nitrogen isotopes, respectively. The widths and thicknesses of the broomcorn millet chaffs ranged from 1.11 to 2.38 mm and from 0.95 to 2.24 mm, respectively, while those of the foxtail millet chaffs ranged from 0.95 to 1.94 mm and from 0.69 to 1.90 mm, respectively. The δ¹³C and δ¹⁵N values of the broomcorn millet chaffs ranged from −13.0‰ to −12.0‰ and from 15.7‰ to 17.8‰, respectively, while those of the foxtail millet chaffs ranged from −14.0‰ to −12.9‰ and from 15.7‰ to 18.8‰, respectively. The results show correlations between the millet chaff size and the carbon/nitrogen isotopic values, suggesting that water and fertilizer conditions might have significantly affected millet grain yield during the late seventh century in northwestern China.

Broomcorn millet (Panicum miliaceum) is among the earliest domesticated staple crops in the world’s agricultural history and facilitated the development of several early agrarian cultures, particularly those originating in northern China. However, the propagation route of broomcorn millet in China from the Middle Ages to the present remains unclear. The aim of this study is to explore the genetic affinity between ancient and modern millet samples, trace the genetic origins and diffusion pathways of broomcorn millet, and provide insights into its domestication and spread. To achieve this, we sequence ancient DNA from broomcorn millet remains excavated from the Chashan Village cemetery (AD 691) in Gansu Province, China. Phylogenetic and population genetic analyses, integrating ancient and modern millet genomes, reveal a close genetic relationship between ancient millet and contemporary millet from Ningxia Province (445 km away from Chashan Village), suggesting a potential origin for the Chashan millet. This finding aligns with the tomb’s epitaph, which documents the reburial of the tomb’s owner, who was originally buried in Ningxia, and provides important archaeological evidence for understanding the interaction between geopolitical dynamics and the natural environment in northwest China during the late seventh century. Furthermore, outgroup-f3 and D statistics evidence suggests substantial genetic interactions between ancient millet and modern varieties from the Loess Plateau, Huang-Huai-Hai Plain, and Northeast Plain, indicating the dispersal route of broomcorn millet, along with human migration routes, from the northwest to northern China and ultimately to the northeast region, starting from the Middle Ages onward. This study enhances our understanding of millet’s genetic history, offers a novel perspective on burial archaeology, and provides valuable insights into the origins, domestication, and diffusion of broomcorn millet.

As the largest known ancient jade mining site, the Mazongshan Site is crucial for understanding the “West–to–East Jade Transportation” system in ancient China. However, its vast nephrite materials remain poorly characterized mineralogically and geochemically. This study employs a multi-technique approach, including polarized light microscopy, SEM-EDS, XRD, CRS, EPMA, and ICP-MS to analyze Mazongshan nephrite. The results identify tremolite as the principal mineral, with accessory minerals including diopside, apatite, serpentine, calcite, dolomite, graphite, hornblende, epidote, forsterite, and albite, as well as limonite occurring as a secondary mineral formed by oxidation. Its rare earth element patterns show significant negative Eu anomalies, low total REE concentrations, and low levels of Cr, Ni, and Co. These results confirm a metamorphic origin for the deposit. Most significantly, the high compositional affinity it exhibits with Hetian nephrite from Xinjiang, together with evidence of ancient mining, has led us to reconsider the prevalence of nephrite materials used during the Warring States to Han periods.