Lasers reveal forgotten cities on the Silk Road

A team from the Uzbekistan Academy of Sciences used lidar technology to map the area where two medieval cities were discovered.

Nestled in the towering mountains of Central Asia, along the route known as the Silk Road, archaeologists are discovering two medieval cities that may have been bustling with life thousands of years ago.

Lidar image of Tugunbulak, the site of a medieval city in Uzbekistan. (Photo: SAIElab/J. Berner/M. Frachetti).

In 2011, a team of researchers first discovered one of these forgotten cities while hiking in eastern Uzbekistan in search of untold historical stories.

The archaeologists hiked along the riverbed and discovered the burial sites on their way to the top of one of the mountains. When they arrived, a plateau with strange mounds spread out before them. To the untrained eye, the mounds looked unremarkable. But 'as archaeologists, we realized that these were man-made places, places where people lived,' said Farhod Maksudov of the National Center of Archaeology of the Uzbekistan Academy of Sciences.

The ground was also littered with thousands of pottery shards. 'We were amazed,' said Michael Frachetti, an archaeologist at Washington University in St. Louis. He and Maksudov had been searching for archaeological evidence of nomadic cultures that grazed cattle in the mountain pastures. The researchers did not expect to find a 12.1-hectare medieval city in a relatively harsh climate at an elevation of about 2,133.6 meters (7,200 feet) above sea level. The site is called Tashbulak , after the area's current name.

The second site, discovered in 2015, dubbed Tugunbulak , was published Oct. 23 in the journal Nature. Researchers used remote sensing technology to map what they describe as a large, 280-acre medieval city located 3 miles (4.8 kilometers) from Tashbulak and connected to a network of trade routes known as the Silk Road.

To get a detailed look at the land, Frachetti and Maksudov equipped a drone with remote sensing technology called lidar (light detection and ranging). Lidar scanners use laser pulses to map features of the land below. The technology has increasingly been used in archaeology—in recent years, it helped uncover a lost Mayan city sprawled beneath the canopy of the Guatemalan rainforest.

At Tashbulak and Tugunbulak, the result is a topographic map of the sites with inch-level detail. With the help of computer algorithms, manual tracing and excavation, the researchers mapped out subtle ridges that are likely to be city walls and other buried structures.