Isotopic evidence reveals the gradual intensification of millet agriculture in Neolithic western Loess Plateau

The intensification of millet agriculture facilitated the development of ancient civilization in northern China. In Inner Mongolia and the Central Plains, the intensification of millet farming was relatively continuous. However, prior evidence from the western Loess Plateau (WLP) has suggested an indistinct sequence of millet cultivation and a time lag between the initial intensification of millet agriculture and subsequent expansion of millet farming. We report on new stable isotopic data and radiocarbon dates from the Gedachuan site which challenge that interpretation. Our results indicate a gradual intensification and expansion of millet agriculture across the whole WLP. They attest to intensive broomcorn millet-based farming underpinning the emergence and development of the agrarian society in the WLP during the early-middle Yangshao period (∼6300-5500 BP), and to an intensification of the higher-yielding foxtail millet-based farming leading to the rapid growth of population in the WLP and expansion of millet cultivation after 5300 BP.