Stable isotope analysis and differences in diet and social status in northern Medieval Christian Spain (9th–13th centuries CE)

•Stable isotope analysis of different social strata in Medieval northern Iberia.•Observed differences between historical personages, urban communities, and rural communities.•Expanding urban centres and religious networks between 9th and 13th centuries AD manifested in dietary differences.•Possibilities of novel insights from bioarchaeology even during periods covered by historical records.