Strontium isotope analysis of cremated remains from Tongobriga: examining mobility at the western edge of the Roman Empire

The site of Tongobriga (Freixo, Marco de Canaveses, northern Portugal) is located on a hillside along the Tâmega river valley, a tributary of the Douro river. Beginning as an Iron Age fortified settlement, when north-western Iberian Peninsula became part of the Roman Empire it became an important city of the Tarraconensis province. At the end of the first century A.D., Tongobriga may have acquired the status of a civitas capital. Twelve urned and unurned cremation burials were recovered from one of Tongobriga’s necropolises, dated from the first century AD. Strontium isotope (87Sr/86Sr) analysis was undertaken to examine the mobility of ten adult individuals from this necropolis. Taking advantage of recently published and newly measured bioavailable 87Sr/86Sr baseline data for Portugal, the comparison of 87Sr/86Sr from these cremated remains to the wider environment was undertaken. This study provides insights into regional and large scale mobility at the edge of the Roman Empire.