TEHRAN -- The modern city of Mashhad, in northeastern Iran, occupies a landscape whose human history extends far beyond the earliest farming communities. 
Although archaeological research has traditionally focused on prehistoric settlements and the fertile plains surrounding the city, evidence from the wider Kashafrud Basin demonstrates that early human populations occupied this region during the Pleistocene. 
Investigations first reported in the 1970s identified stone artefacts at sites east of Mashhad, establishing the basin as an important area for Lower Palaeolithic research. Subsequent surveys have expanded the known distribution of archaeological sites.
Recent investigations by Ali Sadraei, an archaeologist at the University of Torbat Heydarieh, have drawn attention to another part of this landscape: the foothills of the Khalaj Mountains, south of Mashhad. 
During his fieldwork, including an accidental discovery along a mountain trail, Sadraei identified a concentration of stone artefacts at Sang-e Siah, a rock shelter overlooking the Mashhad Plain. 
The site was reportedly added to Iran’s national heritage register in late 2024 or early 2025, although its archaeological significance requires further investigation.
The setting raises questions about how early human groups used this landscape. Today, the rocky slopes offer expansive views across the plain towards Mashhad. 
During the Pleistocene, changing climatic conditions and river systems would have influenced the availability of water, raw materials and potential routes through the region.
The precise environmental conditions at Sang-e Siah during its period of occupation, however, remain to be reconstructed.
According to Sadraei, preliminary examination has identified similarities between the stone artefacts from Sang-e Siah and assemblages associated with the Lower Palaeolithic of the Kashafrud Basin. 
The use of quartz and the presence of chopping tools are among the reported parallels. No bifacial handaxes have been identified in the assemblage described so far, a distinction that may help refine comparisons with other sites in the region.
Such observations are important, but artefact typology alone cannot establish a precise date. A secure
 chronology requires the relationship between artefacts and their geological deposits to be documented, alongside the application of appropriate dating methods. 
Excavation could also establish whether the finds represent activities undertaken at the shelter itself or material displaced by natural processes.
Sadraei suggests that the evidence may indicate a human presence on the Mashhad Plain as early as approximately 500,000 years ago. 
This is a potentially significant proposition, but it should be treated as a preliminary chronological estimate rather than a confirmed date for the shelter. 
The Kashafrud Basin already contains evidence of much earlier Pleistocene occupation, with published interpretations placing some assemblages at around 800,000 years ago. 
Sang-e Siah is therefore significant not necessarily because it represents the earliest human occupation in the region, but because it may preserve a different kind of archaeological record.
Palaeolithic occupation sites are not confined to caves. Early human groups also used rock shelters and open-air locations, selecting places according to local conditions and the activities undertaken there. 
Rock shelters can offer better protection for archaeological deposits than exposed surfaces, where erosion, sediment movement and subsequent disturbance may disperse artefacts. 
Their preservation potential nevertheless varies considerably, and the stratigraphic integrity of Sang-e Siah remains to be demonstrated through systematic investigation.
The wider region is increasingly recognized as important for understanding hominin movement across the Iranian Plateau and towards Central Asia. 
Research published in Antiquity in 2022 documented 176 Palaeolithic localities in the plains of Ferdows, Sarayan and Qaen in South Khorasan, while a 2026 study reported 24 localities in the Esfarayen Plain of North Khorasan. 
Together, these findings demonstrate that the archaeological record extends well beyond the Kashafrud Basin.
If systematic survey and excavation confirm the initial interpretation, Sang-e Siah could provide valuable evidence for understanding how Pleistocene hominins occupied the landscape around Mashhad. 
For now, its greatest contribution may be to highlight how much of northeastern Iran’s deep human history remains to be investigated.