The hooves of nomads' livestock forged the critical middle link between the civilizations of East and West along the Silk Road, according to new research.
Rather than seeing pastoralists as marginal players in the stories of the great civilizations of Asia and Europe, the new study puts these herders squarely at the center of the ancient transcontinental trade route.
The Silk Road was a conduit for the exchange of goods and ideas at least as far back as the third century BCE. Maps of the route typically resemble modern highway maps: a network of lines connecting cities from Xi'an in the east to Genoa in the west.
In the middle, however, are the mountains of Central Asia. Only slightly smaller than the Himalayas, these mountains formed a "pretty scary barrier," says Washington University anthropologist Michael Frachetti.
The search for the Silk Road's route through that barrier often follows paths of least resistance between cities.
"That makes sense if your destination is the other side," Frachetti says. "But what if that's not your destination?"
Livestock led the way
Herder communities have lived in these mountains for millennia, Frachetti notes. Even today, these groups migrate up and down the mountains as the seasons change.
"Their number-one priority isn't taking the easiest path," he explains. "Their number-one priority is feeding their animals along the way."
As they travel from pasture to pasture, they meet, trade and intermarry with other pastoralist communities.
"They get up to these summer pasture zones where there's a lot of populations coming up from different areas," Frachetti says. "They're coming up with their families, with their sons and daughters that want to get married." Goods are exchanged and bonds are formed. "Think of them like festivals," he adds.
Studying present-day herder communities in Kazakhstan, Frachetti had previously modeled how Bronze Age herders may have moved through the mountains of Central Asia from highland pastures in summertime to lowlands in winter.
But that research "wasn't about the Silk Road at all," he says. "People kind of smiled and said, 'that's interesting.' And that's where it sat for 11 or 12 years."
Recently, however, study co-author Tim Williams at University College London mapped 258 known Silk Road sites.
When Frachetti and colleagues lay their map of likely livestock routes over Williams' map of Silk Road sites, they lined up remarkably well.
"There's kind of a moment of truth where you say, 'Okay, how much do they intersect?' And the intersection was surprising," he says.
The research suggests that long before traders crossed the continent in caravans, there was a web of interconnections through the mountains that later became a crucial link in the Silk Road.
"It takes us away from this image of the Silk Road as a highway and turns us towards an image of the Silk Road as a social network," Frachetti adds.
The study, which appears in the journal Nature, "changes the playing field," says Dan Rogers, curator of archaeology at the Smithsonian National Museum of Natural History, who was not part of this research.
The nomads of Central Asia are portrayed as bloodthirsty barbarians everywhere, from ancient Chinese literature to modern movies about Genghis Khan, Rogers says. "What we're finding is a much more complicated picture."
The next step, he adds, is field work that connects what the maps say to what actually happened on the ground.
"Let's go a bit deeper into what the archaeology shows us," he says. "What evidence do we have for how the routes were being used? We'd have to do some excavations."
Frachetti says the new research is "a model against isolationism." The Silk Road connected not only the disparate civilizations of East and West, but also did so by weaving in previously marginalized societies of nomads.
"Through interaction with culturally diverse populations, a greater aggregate civilization arose," he says. "That's a pretty powerful notion."