For thousands of years, people have been using plants with medical and psychoactive effects. In Saudi Arabia, archaeologists have now discovered the world’s oldest proof of the use of steppe diamonds (Peganum Harmala) as a smoke. 2700-year-old residues in incense vessels from the Qurayyah oasis suggest that seeds of this plant were already burned at that time. The smoke generated was probably used primarily because of its medical and antibacterial effect.
The use of plants as medicinal herbs and drugs has a long tradition in human history. In almost all cultures, people used such plants to heal diseases, for cleaning and as an intoxicating and consciousness -expanding drugs in rituals and religious ceremonies – from opium to psychoactive fungi to hallucinogenic planting stud Ayahuasca in South America. But especially with cultures that have not left any written records, the knowledge of these practices and their roots has often been lost. Researchers are therefore dependent on archaeological finds, for example in the form of substance residues in old vessels.
Chemical search for traces in iron Age incense vessels
Archaeologists led by Barbara Huber from the Max Planck Institute for Geoanthropology in Jena have now also used this approach. For their study, they have examined residues that were found in iron-age smoking vessels of the Qurayyah oasis in northwestern Saudi Arabia. “This place was an important city -like center in the Bronze Age and Iron Age,” explain Huber and her colleagues. During excavations in Qurayyah, numerous shells and vessels were also discovered in which substances were apparently burned. Some of these incense vessels were found in living rooms and kitchens, others in cellars.
In order to find out what was burned in these vessels at the time, the team analyzed the residues using a combination of the latest chromatography and mass spectrometry. This combined analysis technique enables even tiny, chemically degraded traces of plant residues. “With this integration of biomolecular analyzes with archaeological methods, we not only managed to identify the type of plants that people used at the time, but also why, how and where they did,” explains co-author Marta Luciani from the University of Vienna. “This allows us to have a unique insight into botanical practices that were central to life at the time, but are usually hardly preserved archaeologically.”
Residues of the steppe motto
With the help of these analyzes, the team discovered residues of several alkaloids in the incense vessels, which come from the psychoactive medicinal plant Peganum Harmala – also known as steppe motto or harl. This robust herb, which is adapted to dry locations, is widespread from southern Europe and the Middle East to Asia and also grows in Saudi Arabia. It has been known for a long time that it has been appreciated in many places for its medical effect. This is how the seeds of the steppe scissors have an antibacterial, anti -inflammatory, pain -relieving and anesthetic effect. They cause hallucinations in a higher dose. The residues in the smoked vessels of the Qurayyah oasis now show that these plants were also used there 2700 years ago.
“This not only represents the first evidence of the steppes in the Iron Age Arabia, but also the oldest radiometrically dated evidence of the use of Peganum Harmala as a smoke,” write Huber and her colleagues. The proof also underlines the far back cultural and medical importance of the steppe scissors in this region. Because it is still used in Saudi Arabia today in traditional medicine and for scarding in households. “Scientifically, this is an important step because we can now better understand how these communities combine their medical knowledge with the local flora,” says Huber.
Smoke as a healing and cleaning agent
But why was the plant used in the Iron Age Qurayyah? “A plausible hypothesis is the use for medical and therapeutic purposes,” explain the researchers. The inhaled smoke could have provided patients and have made it easier to combat infections. It would also be conceivable that people used the antibacterial smoke of the steppe scissors to clean and disinfect their rooms. “Another tradition is the burning of steppe motto seeds for ritual cleaning to ward off evil,” explain Huber and her team. However, it speaks against this that the incense vessels were found primarily in living rooms, kitchens and cellars, but not in graves or temples. Use of the herb and its seeds as a hallucinogen would also be conceivable, but it should have been difficult when burning and inhaling the smoke to meet the right dose for this psychoactive effect.
Huber and her colleagues therefore consider practical use of the steppe scissors for medical and cleaning purposes to be more likely. In any case, the discovery of the combustion residues of Peganum Harmala underlines how far the historical roots of the traditional use of this plant went back. “Due to joint research, we not only preserve the archaeological artifacts, but also contributes to the preservation of intangible cultural heritage-that is, the knowledge passed over over generations that is still alive in the local communities,” says co-author Ahmed Abualhassan from Saudi Arabian Ministry of Culture.
Source: Max Planck Institute for Geoanthropology; Specialist articles: Communications Biology, DOI: 10.1038/S42003-025-08096-7
