Throughout the Middle Ages, the Byzantine Empire dominated the production and commerce of silk in Europe. For centuries, silk contributed heavily to the Byzantine economy, while Costantinople was the main silk-weaving center in all of Europe. Byzantine silk was a prestigious commodity sold at high prices, and was known for its bright colors and complex designs. While the Byzantines got all the praise, prestige, and economic benefits of silk production, the truth is that the secret of silk was actually stolen from China.
The production of silk began in China during the Neolithic, and developed there for centuries. Silk is obtained from the cocoons of the larvae of some insects, most notably the mulberry silkworm, which was domesticated in China since at least the 4th millennium BCE. The cultivation of silkworms to produce silk, known as sericulture, was confined to China for millennia, and how the fabric was obtained remained a closely guarded secret for a long time.
Meanwhile, silk became a popular luxury fabric and was in great demand in all areas accessible to Chinese merchants. While some silk products already reached the Mediterranean since around 1000 BCE, the commerce of silk between China and the West took off with the development of the Silk Road. This trade network began with the expansion of the Han dynasty of China into Central Asia in the 2nd century BCE (read how the Silk Road was actually established after a dispute over horses here), and silk soon became a widely sought-after luxury product in the Roman Empire.
While the Silk Road allowed many kinds of products to be exchanged between East and West, silk was the most profitable good for Chinese merchants, but also for the Parthians and the states of Central Asia, which acted as intermediaries between China and Rome. Silk became so popular in Rome that the Roman Senate even tried in vain to ban it, because the import of this fabric resulted in huge amounts of gold leaving the empire, and using silk was seen at some point as a sign of decadence and immorality.
Court ladies preparing silk in a Chinese painting from the 12th century.
China mantained a monopoly on sericulture for centuries, but over time the production of silk began to expand to Korea, Japan, Central Asia, and India. However, people in the West still ignored where silk came from. At first, the Romans were convinced that the Chinese took the fabric from tree leaves, and only in the 1st century CE Pliny the Elder was able to determine that silk came from silkworms. Despite this, the Romans still didn’t know how to actually produce silk.
With the fall of the Han dynasty, the Parthian Empire, and the Western Roman Empire, the stability of the Silk Road was at risk, and commerce declined. The rise of the Sasanian Empire and its constant conflicts against the Byzantines resulted in a restriction of commerce between East and West. Importing silk to Europe became increasingly difficult and expensive, as the Persians closely controlled trade passing through their territory and would supend the flow of products in times of war. In the 6th century, Byzantine emperor Justinian I attempted to create new trade routes that avoided Sasanian territory, going north through Crimea, or south through Ethiopia. However, these new routes failed, so the Byzantines had to find another way to obtain silk.
According to the 6th-century historian Procopius, two monks of the Nestorian Church, who were returning to Costantinople after preaching Christianity in India, approached Justinian, claiming that they could solve the silk problem. The emperor promised them gifts, and the two monks traveled to China around the year 552. While they were there, they were shown the intricate methods for raising silkworms and producing silk, and learned all their secrets.
Since silkworms are very delicate and can easily die if they are not kept at an ideal temperature, the Chinese didn’t expect that the monks would be able to take them out of China. However, the monks took either silkworm eggs or very young larvae and hid them inside bamboo canes, and were also able to take away some mulberry, which the worms ate. While they were traveling back to Costantinople, the monks were helped by people from Central Asia, and under the monks’ care, the silkworms survived and grew. When the monks arrived in Costantinople, the silkworms were alive and healthy, and even able to reproduce.
Byzantine Emperor Justinian I receives the smuggled silkworms from the two monks, depicted in an engraving from around 1595.
The successfully smuggling of silkworms from China to the Byzantine Empire is considered one of the earliest known cases of industrial espionage, and contributed to the growth of the Byzantine economy. Shortly after the expedition, various silk production centers were established throughout the Byzantine Empire, and thus the monopoly of China was broken and the restrictions of the Persians were avoided. For six centuries, the Byzantines held a monopoly over the commerce of silk in Europe, and this fabric was one of their most profitable products.
The Byzantine monopoly crumbled in the 12th century when, during the Second Crusade, Roger II of Sicily attacked Corinth and Thebes, two important centers of silk production. The weavers and their equipment were taken to Southern Italy, and the regions of Sicily and Calabria began to make their own silk. Soon afterwards, sericulture spread to all of Europe after the Sack of Costantinople in 1204, and was later brought around the world by the Europeans.