Geological surveys conducted at Mongolia’s Oyut Deposit have unexpectedly revealed a series of ancient nomadic burial mounds, shedding new light on funerary traditions that span from the Bronze Age to the medieval period. What began as a search for copper has instead exposed a ritual landscape shaped by steppe communities more than three millennia ago.
The discovery was reported by MONTSAME, following heritage assessments carried out during large-scale mineral exploration in central Mongolia. The burial sites were identified within the Oyut Deposit, located across parts of Orkhon and Bulgan aimags—regions long recognized as cultural heartlands of Inner Asia.
From mineral wealth to ancient graves
Exploration at the Oyut Deposit began in 2023 under a government permit held by the state-owned Erdenet Mining Corporation. Geological studies confirmed an estimated 357 million tonnes of ore containing more than 1.1 million tonnes of pure copper, placing Oyut among Mongolia’s most significant recent mineral discoveries.
Yet during field surveys in 2024, geological teams encountered stone-covered mounds scattered across the exploration area. These features were quickly identified as khirgisuur—ancient burial monuments associated with nomadic societies. In line with national cultural heritage legislation, industrial activity in the affected zones was immediately suspended, and archaeologists were invited to conduct systematic investigations.
Excavation results span millennia
Archaeological fieldwork was carried out in cooperation with the Institute of Nomadic Archaeology at the National University of Mongolia. Over several months, researchers excavated and documented ten burial mounds, completing a comprehensive report by October.
Of the ten graves, four were securely dated to the Bronze Age, four remain undated pending further analysis, and two were attributed to the medieval period, roughly between the 8th and 13th centuries. Despite the region’s harsh continental climate, preservation—particularly in the Bronze Age burials—was described as notably high.
Artifacts recovered from the graves included bronze toli (mirrors), felt fragments, animal bones, and other funerary offerings. Such assemblages are characteristic of steppe nomadic burial customs, where personal belongings and symbolic objects accompanied the deceased into the afterlife.
What is a khirgisuur?
The term khirgisuur refers to a distinctive type of burial mound widely distributed across Mongolia and parts of Inner Asia. Typically dating to the Late Bronze Age, these monuments consist of stone-covered mounds often surrounded by satellite features such as standing stones or sacrificial animal remains. Archaeologists increasingly interpret them not only as graves, but also as ceremonial landmarks that reinforced social memory and territorial identity among mobile pastoralist communities.
The presence of khirgisuur at the Oyut Deposit strengthens the view that Orkhon and Bulgan aimags functioned as long-term corridors of movement and ritual activity for ancient nomadic groups.
A wider historical landscape
The broader Orkhon Valley is already recognized as a UNESCO World Heritage Site for its role in the rise of steppe empires, including the Turkic Khaganates and later the Mongol Empire. The newly documented burial mounds add further depth to this landscape, demonstrating continuity in ritual practices from the Bronze Age through the medieval period.
In total, archaeological research associated with the Oyut exploration covered more than 1,000 hectares, making it one of the more extensive heritage assessments linked to mining activity in recent years.
Development and preservation
As Mongolia continues to balance economic development with the protection of its archaeological heritage, discoveries like those at Oyut underline the importance of cooperation between industry, government authorities, and academic institutions. In this case, geological exploration did more than map mineral resources—it reopened a window onto the deep nomadic past of the Eurasian steppe.
Cover Image Credit: Montsame