China, Iran, Afghanistan, Syria, Uzbekistan and India: if you went to any of these places a thousand years ago, you would find goods and produce from the others. But how did they get there and why? This week’s Forum explores the ancient pattern of trading networks which criss-crossed the plains, deserts and mountains of China, Central Asia and points further West, and which encouraged not just the exchange of commodities like silk, paper and horses but ideas and people too. Bridget Kendall talks to Valerie Hansen, professor of history at Yale University who has a particular interest in trade and exchanges across Eurasia; historian Dr. Susan Whitfield who is curator of the Central Asian collections at the British Library in London; and Tamara Chin, professor of comparative literature at Brown University whose work focuses on ancient China. Photo: A man rides a horse overlooking Band-e-Amir lake, through central Afghanistan, on the former Silk Road that once linked China with Central Asia and beyond. Credit: Getty Images