DNA analysis reveals two waves of migration

Testing conducted on remains further proof of Hexi's role as pivotal hub

In a pioneering study, scientists from Fudan University in Shanghai have delved into the ancient DNA of individuals buried in a mass cemetery in Gansu province, revealing compelling insights into the genetic makeup of Hexi Corridor residents dating back over 12 centuries.

The research, the first of its kind, utilized ancient DNA data to explore human migration along the Hexi Corridor, a pivotal hub on the historical Silk Road.

The results of the study, published in mid-December in the Science Bulletin, revealed two major migration waves in the past two millennia.

The Hexi Corridor, primarily located in present-day Gansu, was a narrow yet crucial link connecting the heartland of ancient China — the Central Plains — to the Western Territory, encompassing areas such as the current Xinjiang Uygur autonomous region and parts of Central Asia. Characterized by its lofty mountains and arid deserts, the ancient pathway was dotted with cities founded along short rivers fed by melted snow.

Historical documents attest to the Hexi Corridor's significance as a crossroads where Western and Eastern civilizations converged through trade, religion and occasional conflicts following the establishment of the Silk Road during the Han Dynasty (206 BC-AD 220).

As technological advances in molecular biology open new avenues for exploration, archaeologists are increasingly drawn to analyzing DNA samples from ancient tombs to validate historical accounts or uncover previously undocumented narratives.

Led by Wen Shaoqing from Fudan University's Institute of Archaeological Science, the team successfully extracted DNA data from teeth and temporal bones found at two sites in Gansu — the Heishuiguo site near Zhangye in the central part of the Hexi Corridor, and the Foyemiaowan site near Dunhuang in the western part of the pathway.

The DNA analysis, encompassing 25 individuals from the Han to the Tang Dynasty (618-907), pinpointed two outliers from the Foyemiaowan site, dating to the Wei Dynasty (221-265) and the Tang. Further scrutiny revealed one had approximately 50 percent western Eurasian ancestry and the other 30 percent, suggesting the individuals were likely descendants of unions between western Eurasian women and local men.

Despite being interred in a mass cemetery, the individuals received equal treatment from their families, indicating the openness and tolerance of ancient Dunhuang, a researcher told Xinhua News Agency. The discovery aligned with materials found in the Mogao Caves in Dunhuang, reflecting the diverse cultural elements in the area at that time.

The team's comparative analysis of data samples and present-day genetics of Hexi Corridor residents led to the conclusion that contemporary Han Chinese in Gansu and specific ethnic groups in the corridor, such as the Dongxiang, Bonan, and Yugur, carry more western Eurasian lineages than their ancient counterparts.

The study identified a significant genetic amalgamation approximately 600 to 1,000 years ago, a period coinciding with the expansion of the Mongol Empire in the early 13th century. Historical records suggest that Genghis Khan and his sons recruited soldiers and artisans from Central and Western Asia during that time, with some settling in the Hexi Corridor. The Yuan Dynasty (1271-1368), established by Genghis Khan's grandson Kublai Khan, further contributed to migration as it defended the Hexi Corridor.

The team said the genetic mix could be partially attributed to those migrations. The western Eurasian elements from the latter period displayed no discernible gender inclination, indicating migration to the Hexi Corridor likely occurred in family units.

Experts said the second major migration period was marked by a significant shift in the gene pool. The first, occurring from the late Neolithic period to the Han Dynasty, witnessed large-scale migration organized by Han rulers in response to the establishment of the Silk Road.

Historical records say migration facilitated by Chinese explorer Zhang Qian's visit to the Western Territory from 138 BC resulted in the creation of the Silk Road. Han rulers moved hundreds of thousands of people, including soldiers, from the mid-lower reaches of the Yellow River to cultivate plants, establish counties and defend the corridor. DNA data has now corroborated those historical records, affirming major genetic changes resembling those found in people from the lower reaches of the Yellow River.

Communication between the East and the West in ancient times has always been a hot topic among researchers, Wen said, adding that the team will continue to explore how the process evolved over a longer period or across larger areas.