Archaeologists use drone-based LiDAR to uncover medieval Silk Road cities in Uzbekistan

A study published in the journal Nature last week unveiled the medieval city of Tugunbulak for the first time, shedding new light on the history and importance of mountain cities along the Silk Road. An international team of archaeologists, led by Michael Frachetti, Professor of Archaeology at Washington University in St. Louis, and Farhod Maksudov, Director of the National Center of Archaeology of Uzbekistan, conducted 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. Over the course of 22 drone flights 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 mountainous areas of the Silk Road.

"We were quite surprised when the image was compiled, as the high resolution reveals so much about the structure of the cities and with such clarity," said Michael Frachetti, according to El Cronista. The use of LiDAR technology allowed the researchers to obtain high-resolution maps that would have taken more than a decade to produce manually. "It would have taken us a decade to map such large sites manually," Frachetti stated, highlighting the significance of their technological advancements.

Tugunbulak is the larger of the two settlements, covering approximately 120 hectares and containing over 300 unique structures, including watchtowers, fortresses, and plazas. Preliminary excavations suggest that Tugunbulak could have functioned as a factory where local metallurgists transformed rich deposits of iron ore into steel. "Iron was key to the production and trade of weaponry," according to the Washington Times. The metal industry, along with trade in animals such as sheep and cattle, would have been a central feature of Tugunbulak's economy.

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

Despite their high elevation and harsh climate, Tashbulak and Tugunbulak were not merely 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, emphasizing the unique erosion dynamics in the region that made these scans particularly effective.

The discoveries challenge previous assumptions about the Silk Road trade routes. Many experts had thought that the famous Silk Road passed only through the lowlands, but research indicates that highland areas played an important role during the medieval period. "While typically seen as barriers to Silk Road trade and movement, the mountains actually were host to major centers for interaction," Frachetti said, according to the Washington Times. "Animals, ores, and other precious resources likely drove their prosperity."

The LiDAR scans revealed an extensive layout hidden beneath the grassy landscapes and mountains, with Tugunbulak being six times larger than previously estimated. "We're like, 'Oh my gosh, this place is humongous,'" Frachetti exclaimed, as reported by Smithsonian Magazine.

Farhod Maksudov commented, "We have realized that this was a large urban center, which was integrated into the Silk Road network and dragged the Silk Road caravans toward mountains because they had their own products to offer," according to livescience.com. This suggests that traders were drawn to the mountains, contrary to the traditional view of trade routes avoiding such terrains.

The research also highlights the innovative use of LiDAR technology in archaeology. A LiDAR scanner uses laser pulses to map land features 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, the LiDAR scans revealed some of the highest-resolution images ever published of archaeological sites, resulting in a relief map with inch-level detail that showed evidence of numerous structures, plazas, fortifications, roads, and habitations.

"The final high-res 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 did not participate in the research, said, "It's a pretty remarkable discovery," highlighting the significance of the findings. He noted that high-altitude urban sites are unusually rare in the archaeological record due to the unique challenges of the natural areas and technological requirements for people to form large communities in mountainous areas.

Sanjyot Mehendale, chair of the Tang Center for Silk Road Studies at the University of California, Berkeley, stated, "The Silk Road's trading networks were very, very fluid," as reported by Smithsonian Magazine. "Societies like Tashbulak and Tugunbulak ultimately became integral to a network that stretched all across Eurasia," she added.

Looking ahead, Frachetti hopes to continue investigating high-altitude settlements along the ancient trading 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