Astonishingly large and remote: Two important cities along the medieval Silk Road once sat high in the mountains of Central Asia, researchers report. This emerges from drone-assisted LIDAR investigations, which were able to detect impressive urban structures at the two previously discovered sites. The researchers say that the discoveries shed light on the complex structure of the ancient trade connection that once connected Europe with East Asia.
For many centuries, goods, people, ideas and even diseases traveled along this legendary route from East to West and vice versa: The Silk Road was a branched network of paths that connected China with the Mediterranean since ancient times and played a major role in long-distance trade until the Middle Ages. How this old exchange system worked and what role settlements and certain regions played in the Silk Road area has long been the focus of research. Researchers led by Michael Frachetti from Washington University in St. Louis are also dealing with these questions.
Their current study is now based on previous discoveries as part of researching the routes of the Silk Road through the mountainous regions of Central Asia: between 2011 and 2015, Frachetti and his colleagues came across traces of two settlements that are located about five kilometers apart in southeastern Uzbekistan. The location seemed astonishing, because the archaeological sites are located in rugged terrain at an altitude of 2,000 to 2,200 meters above sea level. Previous findings indicate that they flourished from the 6th to the 11th centuries and were part of the medieval Silk Road system. However, it has so far remained unclear what size and significance the two places named Tashbulak and Tugunbulak had. At first glance, the archaeological character of the grassy landscape at the sites cannot be recognized.
LIDAR reveals what is hidden
In order to track down hidden settlement structures, the researchers have now used “Light Detection And Ranging” (LIDAR) technology. The landscape at the two locations was scanned with lasers from drones. The topography of the subsurface could then be recorded with a high level of detail from the reflected rays. “These are some of the highest resolution LIDAR images of archaeological sites ever published,” says Frachetti. Computer analyzes could then be used to obtain clues about the hidden traces of former man-made structures.
As the team reports, a surprisingly impressive picture of the two archaeological sites emerged: Tashbulak and Tugunbulak were therefore not simple outposts or rest stops, but urban centers. Streets, squares, houses and fortifications emerged. “The smaller city of Tashbulak covered about twelve hectares, while the larger Tugunbulak was as large as 120 hectares, making it one of the largest regional cities of its time,” says Frachetti. In detail, it was revealed that Tugunbulak had watchtowers connected to walls along a ridgeline. There was also a kind of fortress in the center. The smaller Tashbulak also had such a citadel, surrounded by dense architecture, the team reports.
Surprisingly urban centers
“These were apparently important urban centers in Central Asia,” Frachetti said. But why were they created in this remote mountain landscape? The researchers suspect that both places were built to take advantage of nearby ore deposits and pastures, while the mountainous terrain could also serve as defense. “The Silk Road was not just about the end points in China and the West. Although the mountains are usually viewed as a barrier to trade and movement on the Silk Road, they were also arguably important centers of interaction. Animals, ores and other valuable resources were probably the reason,” says Frachetti.
As the team reports, in the case of Tugunbulak, there is already evidence of the city’s economic base: Preliminary excavations at one of the fortified structures suggest that this building, protected by three-meter-thick rammed earth walls, housed a metal forge that may have produced iron ore from the region processed into steel.
Finally, Frachetti highlights the potential of LIDAR technology in researching the former Silk Road system: The same combination of on-site detective work and drone-based LIDAR can also reveal hidden settlement structures elsewhere. “This could change our view of urban development in medieval Asia,” says Frachetti.
Source: Washington University in St. Louis, specialist article: Nature, doi: 10.1038/s41586-024-08086-5