WASHINGTON: The Great Silk Road that spans across many countries including India was carved by nomads moving herds to lush mountain pastures nearly 5,000 years ago, long before Marco Polo traversed the vast trans-Asian trade route, a new study has found.
The study combines satellite analysis, human geography, archaeology and Geographic Information Systems (GIS) to show that 75 per cent of ancient Silk Road sites across highland Inner Asia fall along the paths its model simulates as optimal for moving herds to and from prime mountain meadows.
"Our model shows that long-term strategies of mobility by highland nomadic herders structured enduring routes for seasonal migrations to summer pastures, which correspond significantly with the evolving geography of 'Silk Road' interaction across Asia's mountains," said Michael Frachetti, associate professor at Washington University in the US.
For over a century, the Silk Road has intrigued modern historians who wish to understand the emergence of the world's most complex ancient overland trade system. "The locations of ancient cities, towns, shrines and caravan stops have long illustrated key points of interaction along this vast network, but defining its many routes has been far more elusive," Frachetti said.
Scholars have previously traced Silk Road trade corridors by modelling the shortest "least-cost" paths between major settlements and trade hubs. This connect-the-dots approach makes sense in lowland areas where direct routes across arid plains and open deserts correlate with ease of travel between trade centres. However, it is not the way highland pastoralists traditionally move in rugged mountain regions, Frachetti said.
"The routes of Silk Road interaction were never static, and certainly not in the mountains," Frachetti said. "Caravans traversing Asia were oriented by diverse factors, yet in the mountains their routes likely grew out of historically ingrained pathways of nomads, who were knowledgeable and strategic in mountain mobility," he said.
"Archaeology documents the development of mountain-herding economies in highland Asia as early as 3000 BC, and we argue that centuries of ecologically strategic mobility on the part of these herders etched the foundational routes and geography of ancient trans-Asian trade networks," Frachetti said.
To test this theory, researchers designed a model that simulates highland herding mobility as "flows" directed by seasonally available meadows. Although the model is generated without using Silk Road sites in its calculations, the pathways it projects show remarkable geographic overlap with known Silk Road locations.
Researchers studied nomadic herding cultures and their ancient trade networks around the world. The field work showed that these societies had inter-continental connections spanning thousands of years, a phenomenon traced to the antiquity of cross-valley pathways that, once engrained, formed the grassroots network that became the Silk Road. The study was published in the journal Nature.