Metabolic profiling reveals first evidence of fumigating drug plant Peganum harmala in Iron Age Arabia.

The utilization of medicinal and psychoactive plants in the past represents a pivotal intersection of culture, health, and biodiversity. While such plants in Arabia have been known from classical and medieval textual records, this study provides material evidence of the use of one such plant for fumigation already in the Iron Age. Through metabolic profiling of organic residues recovered from archaeological artefacts at the oasis of Qurayyah, Northwest Arabia, we identified the drug plant Peganum harmala. Renowned for its antibacterial, psychoactive and multiple therapeutic properties, its presence highlights the deliberate utilization of local pharmacopeia by ancient communities. This discovery represents not only the first evidence for its use in Iron Age Arabia, but also the most ancient, radiometrically dated material evidence of Peganum harmala being used for fumigation globally. Beyond their health benefits, these plants were also valued for their sensory and affective properties. Documenting, understanding and preserving these ancient knowledge systems enriches our understanding of ancient traditions while safeguarding the region's intangible cultural heritage.