Archaeologists use drone-based LiDAR to uncover medieval Silk Road city

A study published in the journal Nature last week revealed the medieval city of Tugunbulak for the first time, shedding new light on the history and importance of mountain towns along the Silk Road. An international team of archaeologists, led by Michael Frachetti, professor of archeology at Washington University in St. Louis, and Farhod Maksudov, director of the National Archaeological Center of Uzbekistan, led the research that brought this ancient city to light.

Using cutting-edge drone-based LiDAR technology, the team surveyed a vast territory in eastern Uzbekistan. During 22 flights with drones equipped with LiDAR sensors, they captured images that revealed two unexpectedly large urban settlements: Tugunbulak and Tashbulak. These medieval cities, located at an altitude of 2,000-2,200 meters above sea level, are among the largest ever documented in the highlands of the Silk Road.

“We were quite surprised when the image was compiled because the high resolution reveals so much about the structure of cities and with such clarity,” said Michael Frachetti, according to El Cronista. The use of LiDAR technology allowed researchers to obtain high-resolution maps that would have taken more than a decade to produce by hand. “It would have taken us a decade to manually map sites this large,” Frachetti said, noting the importance of their technological advances.

Tugunbulak is the larger of the two settlements, covering approximately 120 hectares and containing over 300 unique structures, including watch towers, fortresses and markets. Preliminary excavations suggest that Tugunbulak may have functioned as a factory where local metallurgists turned rich deposits of iron ore into steel. “Iron was the key to arms production and trade,” according to the Washington Times. The metallurgical industry, along with the trade in animals such as sheep and cattle, would have been a central feature of Tugunbulak’s economy.

Spread over about 12 hectares, Tashbulak includes a fortified citadel and a large cemetery with 400 tombs, reflecting early Islamic influence and the spread of Islam in the region. The medieval settlement is believed to have been linked to the Karakhanid Empire, a Turkic khanate of the Karluks that ruled Central Asia from the 9th to the early 13th century AD.

Despite their high altitude and harsh climate, Tashbulak and Tugunbulak were not just outposts or rest stops, but cities with their own economies. “These are some of the highest resolution LiDAR images of archaeological sites ever published,” noted Frachetti, noting the unique dynamics of erosion in the region that made these scans particularly effective.

The findings challenge previous assumptions about Silk Road trade routes. Many experts believed that the famous Silk Road only passed through the lowlands, but research indicates that the highlands played an important role in the medieval period. “Although they are usually seen as barriers to trade and traffic on the Silk Road, the mountains were actually home to major centers of interaction,” Frachetti said, according to the Washington Times. “Animals, ores, and other precious resources probably determined their prosperity.”

LiDAR scans revealed a sprawling feature hidden beneath grassy landscapes and mountains, with Tugunbulak six times larger than previously estimated. “We’re like, ‘Oh my god, this place is huge,'” Frachetti exclaimed, as reported by Smithsonian magazine.

Farhod Maksudov commented: “We realized that this was a large urban center that was integrated into the Silk Road network and dragged the caravans from the Silk Road to the mountains because they had their own products to offer,” according to livescience.com . This suggests that traders were attracted to the mountains, contrary to the traditional view that trade routes avoided such terrain.

The research also highlights the innovative use of LiDAR technology in archaeology. A LiDAR scanner uses laser pulses to map features of the terrain below, creating topographic images by measuring the time it takes a laser beam to travel between the camera and a surface. At Tashbulak and Tugunbulak, LiDAR scans revealed some of the highest resolution imagery ever published of archaeological sites, resulting in a relief map with inch-level detail that showed evidence of numerous structures, plazas, fortifications, roads and housing.


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“The final high-resolution maps were a composite of more than 17 drone flights over three weeks,” Frachetti said in a statement. “We could really change the map of urban development in medieval Asia,” he added.

Zachary Silvia, an archaeologist at Brown University who was not involved in the research, said, “It’s a pretty remarkable find,” emphasizing the significance of the findings. He noted that high-elevation urban sites are unusually rare in the archaeological record because of the unique challenges of natural areas and the technological requirements for people to form large communities in mountainous areas.

Sanjyot Mehendale, chairman of the Tang Center for Silk Road Studies at the University of California, Berkeley, said, “The trade networks of the Silk Road were very, very fluid,” as reported by Smithsonian Magazine. “Societies like Tashbulak and Tugunbulak eventually became an integral part of a network that spread throughout Eurasia,” she added.

Looking ahead, Frachetti hopes to continue investigating high-altitude settlements along the ancient trade network. “We could really change the map of urban development in medieval Asia,” he said.

Sources: Smithsonian Magazine, livescience.com, Российская газета, RPP noticias, El Cronista, Portafolio.co, Washington Times

This article was written in collaboration with generative AI company Alchemiq