From imperial robes to global trade: how silk spread and scaled Silk, a natural fibre produced by the silkworm, has been used in clothing for many centuries. When silk was first discovered in China over 4,500 years ago, it was reserved exclusively for the use of the emperor, his close relations and the highest dignitaries. Within the palace, the emperor is believed to have worn a robe of white silk; outside, he, his principal wife and the heir to the throne wore yellow, the colour of the earth. Gradually silk came into more general use, and the various classes of Chinese society began wearing tunics of silk. As well as being used for clothing and decoration, silk was quite quickly put to industrial use, and rapidly became one of the principal elements of the Chinese economy. It was used in the production of musical instruments, as string for fishing, and even as the world's first luxury paper. Eventually even the common people were able to wear garments of silk. During the Han dynasty (206 BC–220 AD), silk ceased to be a mere fabric and became a form of currency. Farmers paid their taxes in grain and silk, and silk was used to pay civil servants and to reward subjects for outstanding services. Values were calculated in lengths of silk as they had previously been calculated in weight of gold. Before long, silk became a currency used in trade with foreign countries, which continued into the Tang dynasty (616–907 AD). Silk also entered the Chinese language deeply: of the 5,000 most common Mandarin characters, a substantial number use the "silk" radical. Silk became a precious commodity, highly sought after by other countries from an early date, and it is believed that the silk trade actually existed before the Silk Road was officially opened in the second century BC. An Egyptian mummy with a silk thread in her hair, dating from 1070 BC, has been discovered in the village of Deir el-Medina near the Valley of the Kings, and is probably the earliest evidence of the silk trade. During the second century BC, the Chinese emperor Han Wu Di's ambassadors travelled as far west as Persia and Mesopotamia, bearing gifts including silks. Important finds of Chinese silks have also been made along the Silk Road. One of the most dramatic of these finds was some Tang silk discovered in 1900. It is believed that around 1015 AD Buddhist monks, possibly alarmed by the threat of invasion by Tibetan people, had sealed more than ten thousand manuscripts, silk paintings, banners and textiles in caves near Dunhuang, a trading station on the Silk Road in north-west China. Some historians believe the first Europeans to see the fabric were the Roman legions of Marcus Licinius Crassus, Governor of Syria. According to certain accounts of the period, at an important battle near the Euphrates River in 53 BC, the Roman soldiers were so startled by the bright silken banners of the enemy that they fled in panic. Yet, within decades Chinese silks were widely worn by the rich and noble families of Rome. The Roman Emperor Heliogabalus (218–222 AD) wore nothing but silk. By 380 AD, the historian Ammianus Marcellinus reported that the use of silk, once confined to the nobility, had spread to all classes. In spite of their secrecy about production methods, the Chinese eventually lost their monopoly on silk production. Knowledge of silk production reached Korea around 200 BC with waves of Chinese immigrants; after 300 AD it travelled westward and the cultivation of the silkworm was established in India. Around 550 AD silk production reached the Middle East. Records indicate that two monks from Constantinople (modern-day Istanbul), capital of the Byzantine Empire, appeared at their emperor's court with silkworm eggs they had obtained secretly, hidden in hollow bamboo walking sticks. Under their supervision the eggs hatched into worms, and the worms spun silk threads. Byzantium entered the silk business. The Byzantine church and state created imperial workshops, monopolising production and keeping the secret to themselves. This allowed a silk industry to be established, undercutting the market for ordinary-grade Chinese silk; however, high-quality Chinese textiles continued to achieve high prices in the West. By the sixth century the Persians, too, had mastered the art of silk weaving, developing their own rich patterns and techniques. It was not until the 13th century that Italy began silk production, with the introduction of 2,000 skilled silk weavers from Constantinople. Eventually, silk production became widespread throughout Europe. World silk production approximately doubled during the last 30 years despite the rise of man-made fibres. Before this period, China and Japan were the two main producers, together manufacturing more than half of global output each year. After the late 1970s, China dramatically increased its silk production, and once again became the world's leading producer.