The cities of the Silk Road reached astonishing heights in the mountains of Central Asia

Two towering medieval cities built by mobile herders along Central Asia’s Silk Road trade routes have been hidden in plain sight – until now.

Mountainous regions have traditionally been seen as barriers to trade and communication. But these ancient settlements, located roughly 2,000 meters above sea level, show that herding communities developed a distinct form of urban life where such activities flourished, archaeologist Michael Frachetti and colleagues report Oct. 23. Nature.

“Think of these high-rise cities as nodes in a network that moves power and trade across Asia and Europe,” says Frachetti, of Washington University in St. Louis.

Researchers have discovered buildings and cultural artifacts from only a few ancient settlements located more than 2,000 meters above sea level, such as Peru’s Machu Picchu. Despite the thin air, harsh climate, rugged terrain and limited agricultural land, it now appears that mountainous Central Asia was “an urban area” during the Middle Ages, Frachetti says.

The team focused on two archaeological sites in southeastern Uzbekistan: Tashbulak and Tugunbulak. Centuries of erosion and sediment accumulation have obscured the urban features of both sites, located five kilometers apart, beneath rolling grasslands. Large earthen mounds and pottery shards scattered across the landscape led to the discovery of Tashbulak in 2011 and Tugunbulak in 2015. These finds indicate that Tugunbulak was occupied from the 6th to the 10th centuries. The original inhabitants of Tashbulak arrived in the 8th century.

Using drones equipped with light detection and ranging, or lidar, technology, Frachetti and colleagues mapped the extent and layout of both sites. Lidar laser scans have previously looked through tropical jungles and land cover to reveal ancient urban networks in the Amazon, Central America and Cambodia (SN: 1/11/24; SN: 12/4/23; SN: 29.4.16).

Lidar maps of surface-level ridges on the ground where the walls once stood, augmented by computer reconstructions of those buildings, show that Tugunbulak covered just over a square kilometer. It stood as one of the greatest Central Asian cities of its time, says Frachetti.

The more than 300 structures at Tugunbulak included clusters of buildings with common walls, narrow corridors or roads running between these clusters, walled watchtowers along a ridge, and a central citadel or citadel.

Tugunbulak’s appearance mirrored that of small and large field cities in medieval Asia, researchers say. The hill town citadel, surrounded by a citadel or palace, overlooked a city surrounded by defensive walls.

Tashbulak covered roughly one-eighth of Tugunbulak’s territory, but it was still a vibrant community, Frachetti says. A series of large defensive structures overlooked a wide area of ​​platforms, walls and terraced houses. At least 98 structures identified so far resemble building types discovered at the larger site, researchers say.

Population size is difficult to estimate for both communities. But Frachetti suspects that a relatively constant number of year-round residents periodically swelled during gatherings for special events and commodity exchanges.

Lidar’s discovery of large communities at Tugunbulak and Tashbulak highlights the underappreciated ability of high-altitude cattle groups to band together as early city builders, says archaeologist Michael Fisher of the Max Planck Institute for Geoanthropology in Jena, Germany . The new study shows that “mountain ranges may actually be conduits for cultural and economic transmission, not barriers.”

The mountain ranges present few opportunities for agriculture, however, raising questions about how the populations of Tugunbulak and Tashbulak were fed.

Highland pastures supported herds of cattle, sheep, goats, and horses that could be traded or sold to obtain cultivated foods. Previous excavations at Tashbulak revealed remains of cereals, legumes, nut shells, fruit, fragments of chicken eggshells and cotton seeds. Regular shipments of these foods must have come from field settlements, says Max Planck archaeologist Robert Spengler, who participated in those earlier excavations.

Excavations conducted since 2022 suggest that large-scale iron production occurred at Tugunbulak and Tashbulak, Frachetti says. Iron represented a valuable trade item for the inhabitants of the mountain towns.

These mountain towns may also have provided rest stops for caravans traveling the Silk Road, a set of ancient trade and travel routes that ran from China to Europe. But excavations have not yet confirmed this possibility.