Mobility has long been recognised as a key feature of later prehistoric communities in eastern Eurasia. Isotope analysis of human hair offers new potential for studying individual mobility patterns within these communities. Hair samples from individuals of the Tashtyk culture buried in the Oglakhty cemetery in southern Siberia (third to fourth centuries AD) reveal variations in diet during the last months of their lives. Millet and fish were important in summer and autumn, С3 plants and meat and dairy products at other times of year. The results indicate strong seasonal shifts in diet, and seasonal movement between different areas.