Study pushes back arrival of Chinese silk in Central Asia by nearly 2,000 years

An international research team has discovered that China's domesticated silkworms reached Central Asia nearly 4,000 years ago — almost two millennia before the Silk Road — challenging the conventional narrative of how silk spread across the ancient world and reshaping our understanding of early globalization across Eurasia.

The findings are based on three dried silkworm cocoons and mulberry wood remains excavated at Sapalli Tepe, a Bronze Age site in southern Uzbekistan, by Chinese and Uzbek researchers during fieldwork between 2017 and 2019. The study, conducted by scientists from six institutions in China, Uzbekistan, Germany and the United States, was published in the journal Science Advances on July 23.

Silkworm domestication and silk production technologies originated in ancient China, with genomic and archaeological evidence tracing their origins to between 8,500 and 5,000 years ago. However, when and how Chinese silk first spread beyond the country's borders has long been debated. Many scholars have assumed that its westward transmission could not have begun before the Han Dynasty (206 BC-AD 24), when the Silk Road was established nearly two millennia later.

The new study challenges that long-held view.

"Through protein analysis, we identified the three cocoons as belonging to the domesticated silkworm species Bombyx mori, which cannot survive without human care and mulberry leaves, and dated them to roughly 4,000 years ago," said Xia Qingyou, the study's corresponding author and a professor at Southwest University in Chongqing.

Zhou Xinying, a researcher at the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences who led the study, said the team discovered not only silkworm cocoons but also evidence of mulberry cultivation.

"This means that communities in Central Asia had begun producing silk long before the opening of the Silk Road, demonstrating that this uniquely Chinese invention spread far beyond its homeland," Zhou said.

Soil samples from Sapalli Tepe yielded the three cocoons alongside thousands of plant remains. Scanning electron microscopy revealed fiber structures consistent with Bombyx mori cocoons. The ancient fibers were notably finer than those of modern domesticated or wild silkworms, suggesting they represented an earlier stage of domestication.

Shen Hui, an associate researcher at the Institute of Vertebrate Paleontology and Paleoanthropology, said mulberry charcoal was found at all three sites the researchers excavated — Sapalli Tepe, Djarkutan and Molleli.

"The proportion of mulberry charcoal increased from 10 percent at Sapalli Tepe to 60 percent at Molleli, indicating that mulberry cultivation expanded over time," Shen said.

The team also identified citrus wood, a plant native to the southeastern Himalayas, further supporting links between Central Asia and South Asia, Shen added.

By compiling archaeological records of mulberry across Asia, the researchers proposed that China's sericulture tradition spread along the southern slopes of the Himalayas before reaching Central Asia, rather than through the better-known northern Silk Road corridors.

"This discovery places sericulture within a broader wave of early globalization alongside the spread of millet, wheat, livestock and metallurgy between China, Central Asia and South Asia during the third and second millennia BC," Zhou said.

"It shows that nearly 4,000 years ago, communities across Eurasia were already connected through networks of shared knowledge and technologies — far earlier than previously believed."

The researchers said the findings also raise new questions about whether diverse forms of sericulture existed across Bronze Age Asia.

"This leads us to reconsider the timeline and pathways through which one of China's most transformative inventions reached the wider world," Zhou said, adding that future research will focus on tracing how sericulture continued to develop and diversify after reaching Central Asia.