Common walnut (Juglans regis L.) is an economically important species cultivated worldwide for its wood and nuts. It is generally accepted that J. regia survived and grew spontaneously in almost completely isolated stands in its Asian native range after the Last Glacial Maximum. Despite its natural geographic isolation, J. regia evolved over many centuries under the influence of human management and exploitation and spread throughout Europe via ancient trade routes which enabled long-distance dispersal from Iran and Trans-Caucasus to Central Asia, and from Western to Eastern China.