Map of Eurasia shows the oldest radiocarbon-measured dates (B.C.) for individual grains of barley recovered from each region. Wheat and barley arrived in South Asia about a millennium before they arrived in East Asia. Free-threshing wheats spread to China along a route to the north of the Tibetan Plateau. Naked barley is likely to have been introduced to China via southern highland routes that remain to be identified. Image: Courtesy of PLOS One
