ANN ARBOR—You might not often think about the molars of livestock, but everything from the grass they eat to the water they drink can tell a story about how people lived centuries ago.
An international collaboration led by University of Michigan researchers examined herd management in medieval Kazakhstan using isotopes embedded in the enamel of sheep's molars. They found that people living in the arid region fine-tuned their strategies of animal management in order to succeed in a challenging environment.
The study specifically found that people in the medieval town of Dzhankent fed their flocks dried grass, acquired animals from outside their region for food, and carefully planned when sheep would give birth, which suggests they were trying to ensure milk and milk products like cheese would be available year-round, the researchers say.
"Dzhankent was particularly resilient in that they were flexible in their herd management strategies to keep the population fed year-round," said Kara Larson , doctoral candidate in the U-M Museum of Anthropological Archaeology and lead author of the study published in the journal Archaeometry . "So often we see narratives of urban populations being solely reliant on one method of herd management, so it is exciting to see how adaptive Dzhankent was, both in local herding and in pulling in regionally sourced animals."
From the 7th to 11th centuries CE, Dzhankent, located in southern Kazakhstan, evolved from a fishing and agricultural village to a larger town, serving as a key node on the northern Silk Roads, a network of Asian trade routes. But little is known about how the city sustained itself.
"The Silk Road city of Dzhankent was vital to trade during the 9th and 10th centuries. In order to feed its inhabitants, there was a great diversity in herding strategies and the season of birth of sheep," said Alicia Ventresca-Miller , associate curator of archaeological sciences at the UMMAA. "This indicates inhabitants were trying to extend access to milk products across the year, and were further mitigating risks by having varied pasturing and foddering practices. That is, they were intentionally moving sheep and giving them extra cut grass during lean times."
Flexibility in a challenging environment
Situated within the Aral Sea basin, Dzhankent is surrounded by semi-desert and desert, and dependent on water from the Amu Darya and Syr Darya rivers. During the winter, air from Siberia keeps temperatures at around 14 degrees below zero. Summers are hot and dry, and temperatures hover around 80 degrees. Between 4 and 5.5 inches of rain fall each year.
As sheep eat and drink, isotopes in their food and water become part of their teeth. Determining the composition of isotopes in the sheep's teeth can tell researchers how sheep were pastured, when they gave birth and were culled, and how they were foddered, or fed. To study the herd management practices of people living at Dzhankent, the researchers analyzed the second molars of 16 sheep, sequentially measuring carbon and oxygen isotopes within the enamel.
The researchers then broke the 16 sheep down into six groups based on the combined carbon and oxygen values. There is seasonal variation in oxygen isotope ratios, which are elevated during the summer months and lower during the winter months.
Comparatively, higher carbon isotope ratios indicate consumption of grass during the summer or dry seasons, while lower carbon isotope ratios indicate consumption of plants in the winter or wetter seasons.
Researchers found that sheep likely were bred throughout the year, with the majority of individuals born in the spring months. Breeding sheep throughout the year was likely a strategy to keep them producing milk during the winter months.
"People living at Dzhankent could depend on milk and milk products such as dried, salted cheese curds that served as a source of sustenance during lean times. This is similar to the modern era when people eat qurt, a Kazakh cheese, year round," Ventresca-Miller said. "Based on the diversity of herding practices and extension of sheep birthing periods, we know that this town was resilient."
Archaeometry
Provisioning a Silk Road City: Herd Management Strategies at the Urban Site of Dzhankent, Kazakhstan
28-Jul-2026