Archaeologists have discovered the remains of two medieval towns in the grassy mountains of eastern Uzbekistan, a discovery that could change our understanding of the legendary Silk Road.
Known for the exchange of goods and ideas between East and West, trade routes were long believed to connect cities on the plains.
But thanks to remote sensing technology, archaeologists have discovered at least two highland towns located along a key crossroads of trade routes.
One of these towns, Tugunbulak, a metropolis covering at least 120 hectares, is located more than 2,000 m above sea level, an altitude considered inhospitable even today.
“The history of Central Asia is changing with this discovery,” said archaeologist Farhod Maksudov, who was part of the research team.
The team believes that Tugunbulak and the smaller town, Tashbulak, were bustling settlements between the 8th and 11th centuries, during the Middle Ages, when the region was controlled by a powerful Turkish dynasty.
Today, only 3% of the world's population lives above this altitude. Lhasa in Tibet and Cusco in Peru are rare examples.
The discovery, led by M. Maksudov, director of the National Archeology Center of Uzbekistan, and Michael Frachetti, an archaeologist at Washington University in St. Louis, was made possible using drones and a remote sensing tool known as name lidar, which uses reflected light to create three-dimensional maps of the environment.
Their research was published this week in the scientific journal Nature, and uninvolved experts hailed its importance in shedding light on the lifestyles of nomadic communities.
The team first discovered Tashbulak, the smaller town, in 2011 while hiking in the mountains. They found burial sites, thousands of pottery shards, and other signs that the land was populated.
Historical records hint at towns in the area, he said, but the team didn't expect to find a 12-hectare medieval town at around 2,200m above sea level.
“We were a bit blown away,” Mr Frachetti told the BBC.
Even hiking up there was difficult, he added, as they faced high winds, storms and logistical challenges.
Four years later, a local forest administrator asked the team to study another site near Tashbulak.
“The manager said, 'I think I have this kind of ceramic in my garden.'
“So we went to his house… and discovered that his house was built on a medieval citadel. It was like living in a huge city,” Mr Frachetti said.
The most difficult part of these discoveries was convincing the academic community that these cities existed.
“We were telling people that we discovered this incredible site, and we were skeptical, thinking that maybe it wasn't that big, or that it was just a mound, or a castle… It was the big challenge, how to scientifically document this city to really illustrate what it was all about,” Mr. Frachetti said.
In 2022, the team returned with a drone equipped with a lidar sensor, which peeled away surfaces to reveal walls, guard towers, complex architectural features and other fortifications at Tugunbulak.
Researchers suggest that communities may have chosen to settle in Tugunbulak and Tashbulak to exploit the strong winds and fuel the fires needed to smelt iron ores, which the region was rich in. Preliminary excavations also uncovered production furnaces.
“Anyone who had iron in medieval times was very powerful,” Mr Maksudov said.
But it could also have led to the downfall of communities, he added. This area was once covered in a thick forest of juniper trees, but these could have been cut down to facilitate iron production. “The region has become very ecologically unstable due to flash floods and avalanches,” he explained.
Typically, researchers expected to find evidence of settlements further down the valley, “so these findings are remarkable,” said Peter Frankopan, professor of world history at the University of Oxford.
“What an incredible treasure… showing the deep interconnections that crisscross Asia, as well as the links between the exploitation of natural resources over a millennium ago,” he said.
High-altitude urban sites are “extraordinarily rare” in the archaeological record because communities face unique challenges settling there, said Zachary Silvia, an archaeologist at Brown University.
The team's work makes an “immense contribution to the study of medieval urban planning in Central Asia,” he writes in a commentary on Nature.
