More than 2,500 years ago, horse-mounted nomads expanded their cultural domain across the Eurasian steppe from southern Siberia to Eastern Europe. These tribes had in common that they buried their dead in large tombs often along with elaborate gold jewelry and weapons of superior ability. Most organic materials are lost forever, but objects made of metals survive for millennia. Often made of bronze and gold, these treasures attract looters. During the colonization of Siberia in the eighteenth century, looting became a seasonal job when excavator gangs, sometimes up to 300 strong graves excavated from spring to autumn each year. In order to transport the metals more easily, prehistoric works of art were often fused directly into the place where they had been found.
Application of high resolution satellite images
It has become increasingly difficult to find unbroken tombs. The prices of the archaeological objects of these burials, however, saw a great increase. Gino Caspari, from the Institute of Archaeological Sciences at the University of Bern, analyzed the condition of burials in a difficult-to-access region based on high-resolution satellite imagery. These data help assess the degree of destruction inflicted on archaeological heritage. "We specifically chose an area of interest in Xinjiang, China. We assume that due to the remoteness and the strong presence of security forces in the region, we would find a greater proportion of intact tombs, "explains Caspari. However, this assumption was wrong: "More than 74.5% of the funerals analyzed have already been destroyed and looted," says Caspari.
Archaeological sites severely threatened
Through ground-based research, researchers have been able to show that high-resolution satellite imagery can provide accurate measurement of destruction at a given location. Using time series of different data sets, the serve can be effectively monitored. Caspari has analyzed the data since 2003, and found that since then, the number of looted tombs has increased substantially. "The last untouched archaeological sites of the ancient nomads of the steppes are under imminent threat," says Caspari.
The research, published in the journal Heritage, allows for consistent monitoring of archaeological heritage in remote regions of Central Asia. When the looting at a location is recognized at an early stage, measures for the protection of the tombs can be implemented.