【地理学】遊牧民の通り道がシルクロードの始まりだった

The Silk Roads, an ancient network of trade routes that crossed central Asia, were shaped by the nomadic movements of herders up to 4,000 years ago, a paper in this week’s Nature reveals. The study is the first to quantify the emergence of the Silk Roads both in terms of time and ecology, highlighting the role of non-urban societies in the development of one of the most extensive networks of biological and economic change in human history.

The Silk Roads were a complex network of pathways that stretched from China to the Eastern Mediterranean and beyond, passing through some harsh mountainous terrain along the way. Little is known about how the routes were formed, or the factors that influenced their geography. Michael Frachetti and colleagues modelled the movements of ancient mountain herders, and conclude that the Silk Roads emerged from the tracks formed by ancient herders and their animals as they moved up and down the mountains in search of fresh pasture. Seasonal migrations of nomadic herders formed non-random pathways that went on to define the geography of the Silk Roads.

Previous attempts to model the formation of the Silk Roads were limited because researchers focused on ‘connecting the dots’ between sites already known to be part of the network. Here, the authors took a different approach by adapting hydrological flow algorithms to simulate ‘herd flows’ across rich highland pastures to produce a more detailed map of the Silk Road networks.