Single-year radiocarbon dating in nordic urban archaeology: Ribe and the importance of context

Radiocarbon calibration curves have improved significantly after the discovery of solar particle events and the addition of annual data to calibration datasets. In this study, we provide a new absolute chronology for Viking Age Ribe. 140 radiocarbon dates were calibrated with a purpose-made calibration curve, based on IntCal20 and additional tree-rings measurements for the ninth century. We combine the radiocarbon dates with dendrochronological dates and the site’s detailed stratigraphy, built up of clay floors and activity layers, in a Bayesian age model. We show that long-distance maritime trade began already around AD 750, as evidenced by artefacts imported from Norway. The expansion of trade, especially towards the Middle East, and other aspects of the beginning of the Viking Age such as Berdal style brooches occur in layers dated to AD 790 ± 10. We also identify the clay floor that was in use when the AD 775 solar particle event took place. Finally, we apply the same techniques to radiocarbon dates of other Viking Age samples and sites from the literature. Recent aDNA results help to re-calibrate radiocarbon dates of human bones with greatly increased precision. We also explore the potential of re-calibrating and modelling legacy dates to improve the chronology of individual sites and their relations with other sites. When high-precision radiocarbon measurements are combined with annual calibration curves and high-precision contextual information, radiocarbon dates become precise enough to be a relevant source of information for historical archaeology.