Recent discoveries of rapid changes in the atmospheric 14C concentration linked to solar particle events have spurred the construction of new radiocarbon annual calibration datasets1,2,3,4,5,6,7,8,9,10,11,12,13. With these datasets, radiocarbon dating becomes relevant for urban sites, which require dates at higher resolution than previous calibration datasets could offer. Here we use a single-year radiocarbon calibration curve to anchor the archaeological stratigraphy of aÂ Viking Age trade centreÂ in time. We present absolutely dated evidence for artefact finds charting the expansion of long-distance trade from as far away as Arctic Norway and the Middle East, which we linked to the beginning of the Viking Age at ad"‰790"‰Â±"‰10. The methods developed here enable human interactions and cultural, climatic and environmental changes to be compared in archaeological stratigraphies worldwide.