# Genetic landscape of populations along the Silk Road: admixture and migration patterns

## TL;DR

This study explores the genetic makeup of populations along the Silk Road, revealing admixture patterns and migration events linked to historical movements like the Mongolian expansion.

## Contribution

The study provides a detailed genetic map of Central Asian populations and quantifies historical gene flow along the Silk Road.

## Key findings

- A West-East genetic subdivision was observed with a shared component in Central Asia, Europe, and the Near East.
- Up to 50% genetic contribution from Europe and Asia was identified, with Asian influence dating back ~25 generations in the Eastern Silk Road.
- Migration events were mapped in time and space, showing complex gene flow among six Central Asian populations.

## Abstract

The ancient Silk Road has been a trading route between Europe and Central Asia from the 2nd century BCE to the 15th century CE. While most populations on this route have been characterized, the genetic background of others remains poorly understood, and little is known about past migration patterns. The scientific expedition “Marco Polo” has recently collected genetic and phenotypic data in six regions (Georgia, Armenia, Azerbaijan, Uzbekistan, Kazakhstan, Tajikistan) along the Silk Road to study the genetics of a number of phenotypes.

We characterized the genetic structure of these populations within a worldwide context. We observed a West-East subdivision albeit the existence of a genetic component shared within Central Asia and nearby populations from Europe and Near East. We observed a contribution of up to 50% from Europe and Asia to most of the populations that have been analyzed. The contribution from Asia dates back to ~25 generations and is limited to the Eastern Silk Road. Time and direction of this contribution are consistent with the Mongolian expansion era.

We clarified the genetic structure of six populations from Central Asia and suggested a complex pattern of gene flow among them. We provided a map of migration events in time and space and we quantified exchanges among populations. Altogether these novel findings will support the future studies aimed at understanding the genetics of the phenotypes that have been collected during the Marco Polo campaign, they will provide insights into the history of these populations, and they will be useful to reconstruct the developments and events that have shaped modern Eurasians genomes.