Bulk-bone ancient metagenomics reveals the transport of South Asian fish across the Himalayas in the 8th century CE

Fish was an important component of (pre)historical consumption products. The study of (pre)historical fish products has been impeded by the morphological identifications in zooarchaeological research, based on poorly preserved fish bones. In this study, we applied the Bulk Bone Shotgun Metagenomic (BBSM) approach to unidentifiable bone fragments excavated from the Kongsangqiao site (dated to 652–768 CE) located on the southern slope of the central Himalayas. Among other species, the low-land South Asian fish species Rohu (Labeo rohita) was identified, marking the first discovery of a South Asian fish species on the high-altitude Tibetan Plateau. This new evidence suggests that fish may have been carried by travelers departing from South Asia to provide necessary nutritional sustenance and energy for their long-distance journeys, or was exported from the low-land South Asian plain to the Tibetan Plateau along the ancient Tubo-Nepal Road. The results also show the great potential of ancient DNA analysis on unidentifiable bone fragments in enhancing our understanding of the history of fish utilization.