The first-ever use of drone-based lidar technology in Central Asia has allowed archaeologists to uncover two significant medieval trade cities in Uzbekistan’s mountainous region. These findings, led by Michael Frachetti from Washington University in St. Louis and Farhod Maksudov of the National Center of Archaeology in Uzbekistan, highlight the importance of high-altitude urbanism on the Silk Road. The research was recently published in Nature.
The drone-lidar scans revealed the scale and layout of these cities, located at elevations between 2,000 and 2,200 meters—comparable to Machu Picchu. The cities, Tashbulak and Tugunbulak, are among the largest ever discovered in the region. Tashbulak covers approximately 12 hectares, while Tugunbulak, at 120 hectares, is “one of the largest regional cities of its time,” according to Frachetti. The cities date from the sixth through 11th centuries and played a crucial role in Silk Road trade and highland economies.
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“These would have been important urban hubs in central Asia, especially as you moved out of lowland oases and into more challenging high-altitude settings,” Frachetti explained. “While typically seen as barriers to Silk Road trade and movement, the mountains actually were host to major centers for interaction. Animals, ores, and other precious resources likely drove their prosperity.”
The project, supported by the National Geographic Society, involved a multidisciplinary team that included WashU researchers and collaborators such as Jack Berner, a graduate student in anthropology, and Edward Henry, an assistant professor at Colorado State University. Their efforts provided a detailed view of plazas, roads, fortifications, and habitations that shaped life for both local communities and passing traders.
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“This site had an elaborate urban structure with specific material culture that greatly varied from the lowland sedentary culture,” Maksudov said. The inhabitants of Tugunbulak, according to him, were nomadic pastoralists who maintained a distinct culture and political economy for over a thousand years.
A drone captured images of Tugunbulak in 2018. Photo by Michael Frachetti
Drone-lidar technology is commonly used to map landscapes blocked by dense vegetation, but it also proved valuable in the mountainous terrain of Uzbekistan, where vegetation is sparse. “Drone operation is strictly regulated in Uzbekistan, so this discovery is also thanks to the political support and permissions we received through local partners and government,” Frachetti noted.
The high-resolution scans captured centimeter-level details, which allowed for advanced computer analysis of the cities’ architecture. “These are some of the highest-resolution lidar images of archeological sites ever published,” Frachetti said, crediting the unique erosion patterns in the mountainous environment for preserving the structures so well.
Frachetti and his team first discovered the highland cities using predictive computer models and traditional foot surveys between 2011 and 2015. The use of drone-based lidar, however, greatly accelerated the mapping process. “The final high-res maps were a composite of more than 17 drone flights over three weeks,” Frachetti said. “It would have taken us a decade to map such large sites manually.”
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A drone captured images of Tugunbulak in 2018. Image by Michael Frachetti
The data was compiled into 3D models by Frachetti’s Spatial Analysis, Interpretation, and Exploration (SAIE) Lab, with help from undergraduate student Xiaoyi Liu and Tao Ju, professor of computer science at WashU. Liu and Ju used computational algorithms to analyze the surfaces and predict architectural alignments. The results revealed a vast city that would have been difficult to detect with the naked eye. “The project reflects a truly interdisciplinary effort,” Ju commented. “The analysis techniques have potential applications in many domains that utilize lidar scans.”
Preliminary digging at Tugunbulak has already uncovered one of its fortified structures, a building with three-meter-thick walls that may have functioned as a factory for steel production. The rich deposits of iron ore in the region likely contributed to the city’s industrial economy.
Tashbulak and Tugunbulak, Frachetti concluded, were not just remote outposts. “The Silk Road wasn’t just about the endpoints of China and the West. Major political forces were at play in Central Asia. The complex heart of the network was also a driver of innovation.”
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Looking ahead, Frachetti hopes to apply drone-based lidar to other high-altitude Silk Road settlements. “We could really change the map of urban development in medieval Asia,” he said.
The article, “Large-scale medieval urbanism traced by UAV–lidar in highland Central Asia,” by Michael D. Frachetti, Jack Berner, Xiaoyi Liu, Edward R. Henry, Farhod Maksudov and Tao Ju, appears in Nature. Click here to access it.
The first-ever use of drone-based lidar technology in Central Asia has allowed archaeologists to uncover two significant medieval trade cities in Uzbekistan’s mountainous region. These findings, led by Michael Frachetti from Washington University in St. Louis and Farhod Maksudov of the National Center of Archaeology in Uzbekistan, highlight the importance of high-altitude urbanism on the Silk Road. The research was recently published in Nature.
The drone-lidar scans revealed the scale and layout of these cities, located at elevations between 2,000 and 2,200 meters—comparable to Machu Picchu. The cities, Tashbulak and Tugunbulak, are among the largest ever discovered in the region. Tashbulak covers approximately 12 hectares, while Tugunbulak, at 120 hectares, is “one of the largest regional cities of its time,” according to Frachetti. The cities date from the sixth through 11th centuries and played a crucial role in Silk Road trade and highland economies.
“These would have been important urban hubs in central Asia, especially as you moved out of lowland oases and into more challenging high-altitude settings,” Frachetti explained. “While typically seen as barriers to Silk Road trade and movement, the mountains actually were host to major centers for interaction. Animals, ores, and other precious resources likely drove their prosperity.”
The project, supported by the National Geographic Society, involved a multidisciplinary team that included WashU researchers and collaborators such as Jack Berner, a graduate student in anthropology, and Edward Henry, an assistant professor at Colorado State University. Their efforts provided a detailed view of plazas, roads, fortifications, and habitations that shaped life for both local communities and passing traders.
“This site had an elaborate urban structure with specific material culture that greatly varied from the lowland sedentary culture,” Maksudov said. The inhabitants of Tugunbulak, according to him, were nomadic pastoralists who maintained a distinct culture and political economy for over a thousand years.
Drone-lidar technology is commonly used to map landscapes blocked by dense vegetation, but it also proved valuable in the mountainous terrain of Uzbekistan, where vegetation is sparse. “Drone operation is strictly regulated in Uzbekistan, so this discovery is also thanks to the political support and permissions we received through local partners and government,” Frachetti noted.
The high-resolution scans captured centimeter-level details, which allowed for advanced computer analysis of the cities’ architecture. “These are some of the highest-resolution lidar images of archeological sites ever published,” Frachetti said, crediting the unique erosion patterns in the mountainous environment for preserving the structures so well.
Frachetti and his team first discovered the highland cities using predictive computer models and traditional foot surveys between 2011 and 2015. The use of drone-based lidar, however, greatly accelerated the mapping process. “The final high-res maps were a composite of more than 17 drone flights over three weeks,” Frachetti said. “It would have taken us a decade to map such large sites manually.”
The data was compiled into 3D models by Frachetti’s Spatial Analysis, Interpretation, and Exploration (SAIE) Lab, with help from undergraduate student Xiaoyi Liu and Tao Ju, professor of computer science at WashU. Liu and Ju used computational algorithms to analyze the surfaces and predict architectural alignments. The results revealed a vast city that would have been difficult to detect with the naked eye. “The project reflects a truly interdisciplinary effort,” Ju commented. “The analysis techniques have potential applications in many domains that utilize lidar scans.”
Preliminary digging at Tugunbulak has already uncovered one of its fortified structures, a building with three-meter-thick walls that may have functioned as a factory for steel production. The rich deposits of iron ore in the region likely contributed to the city’s industrial economy.
Tashbulak and Tugunbulak, Frachetti concluded, were not just remote outposts. “The Silk Road wasn’t just about the endpoints of China and the West. Major political forces were at play in Central Asia. The complex heart of the network was also a driver of innovation.”
Looking ahead, Frachetti hopes to apply drone-based lidar to other high-altitude Silk Road settlements. “We could really change the map of urban development in medieval Asia,” he said.
The article, “Large-scale medieval urbanism traced by UAV–lidar in highland Central Asia,” by Michael D. Frachetti, Jack Berner, Xiaoyi Liu, Edward R. Henry, Farhod Maksudov and Tao Ju, appears in Nature. Click here to access it.
Top image: Composite lidar view of Tugunbulak, Image courtesy: SAIElab/J.Berner/M.Frachetti
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