A form of paper was first made in China at sometime between the second century BC and the first century AD during the Han Dynasty as a substitute for expensive wood and silk when the national civil service was set up. The process was formally reported to the Emperor Yuan Hsing by Ts’ai Lun in AD105. The earliest paper may have been made out of the fibres of macerated cloth but this material was soon replaced by fibres from the bark of the mulberry tree (Broussonetia papyrifera). Although a closely-guarded secret, knowledge of the techniques of paper making had spread from Korea (then part of China) to Japan by 600AD. Information seems to have leaked westwards along the trade routes (the ‘Silk Road’) linking China to the Eastern Mediterranean, but it was from paper-making prisoners taken at the Battle of Talas that it really took off. After starting in Samarkand, the main factories were those of Harun al Raschid in Baghdad. From there it continued to Damascus. The technology of paper making then gradually diffused further westwards through the Islamic empire in North Africa, finally reaching Western Europe in the 10th-11th centuries through Southern Spain, which at the time was still under Islamic influence.