How Justinian Stole Silk from China

Industrial espionage is nothing new. The Chinese communists are among the masters of this craft. Ironically, the industry China is still most widely known for, silk, stood at the center of an ancient industrial espionage. At the center of the story stood the emperor determined to restore the glory of old Rome, but to do that, he needed money, piles of it. One source of it came from the east. This is the story of how Justinian stole silk from China.


Silk production, of course, began in China. It seems to have been an old trade. Confucius (551-479 BC) remarked that it was produced as early as the time of the Yellow Emperor, a mythical figure who lived in the third millennium BC, far preceding the earliest historically attested dynasty, the Shang. As we have seen in Greece and Egypt, though, traditional tales are often based on historical truths. The Chinese produced silk for a long time. Physical examples stretching back to the fourth millennium BC have been discovered.

Centuries of warfare hampered the growth of the industry, but by the time of the Persian Wars, exports reached Europe. By Roman times, the Silk Road became established. The Romans (and people long after them) prized it not only for its touch and feel, but because they could also dye it in brilliant hues. Purple silk clothing was so prized that only the emperor could wear it.

The Roman nobility loved it – and only they could afford it – but they had no idea how it was made. Virgil believed that it came from combed leaves. There was a reason for this ignorance. The Chinese emperors kept its production a closely-guarded state secret to maintain their monopolies over it. Despite this, the “trade secrets” eventually leaked to Korea and India, spreading through the immediate region. Yet, the Romans remained ignorant of it.

Enter Justinian.

6th Century Geopolitics

Justinian came to the throne of the Byzantine Empire (officially the Eastern Roman Empire) in 527. From the outset, he vowed to restore Rome’s original borders. Fortunately, he had two great generals, Belisarius and Narses to help him do this. This was a costly undertaking.

Additionally, he also had Rome’s ancient enemy to the east to deal with – the Sassanid Persians. They succeeded the Parthians as the Empire’s foremost peer competitor in its neighborhood. The Persians stood at the epicenter of the Silk Road.

Silk Road Map
Map from the Penn Museum exhibit.

As you can see, the Persians dominated the land route and the sea routes through their control of the Persian Gulf. Only the minor extreme northern route did not go through their land or sea territory.

Justinian greatly desired to find a way to bypass the Persians in the silk trade. The product originating from China (or India, by that point) meant that it needed to be sold and resold multiple times on the long journey, increasing the price dramatically. Worse, each time Romans bought it, they enriched the Empire’s greatest nemesis. It was a clear national security issue.

Justinian initially attempted a trading arrangement with the Abyssinians in northeast Africa to bypass the Persians. He also attempted greater use of the northerly land route. The first attempt proved unsuccessful. The northerly route saw modest success, but because of its longer length, it increased the price. The more competitive Persians remained in control of a great part of the trade. As such, the northerly route proved only mildly satisfactory.

At this point, two monks from the east appeared before the emperor.

The Mission to Steal Silk

From here on, the story reads like a spy novel. These two mysterious, unnamed monks, who were probably affiliated with the Nestorian Church of the East, told Justinian that they could bring silk manufacturing to the Empire, bypassing all the middlemen entirely.

Procopius describes the entire operation as such:

There came from India certain monks; and when they had satisfied Justinian Augustus that the Romans no longer should buy silk from the Persians, they promised the emperor in an interview that they would provide the materials for making silk so that never should the Romans seek business of this kind from their enemy the Persians, or from any other people whatsoever. They said that they were formerly in Serinda, which they call the region frequented by the people of the Indies, and there they learned perfectly the art of making silk. Moreover, to the emperor who plied them with many questions as to whether he might have the secret, the monks replied that certain worms were manufacturers of silk, nature itself forcing them to keep always at work; the worms could certainly not be brought here alive, but they could be grown easily and without difficulty; the eggs of single hatchings are innumerable; as soon as they are laid men cover them with dung and keep them warm for as long as it is necessary so that they produce insects. When they had announced these tidings, led on by liberal promises of the emperor to prove the fact, they returned to India. When they had brought the eggs to Byzantium, the method having been learned, as I have said, they changed them by metamorphosis into worms which feed on the leaves of mulberry. Thus began the art of making silk from that time on in the Roman Empire.

If only it were that simple! First take note that “Serinda” – the “land of silk” is China. This came as a revelation, because the Romans believed the production came from India. The monks also had strategic value as Nestorian Christians, because the Church of the East had establishments along the trade routes between China and the Roman Empire.

That the monks had actually seen the process of making the material, was an extraordinary blessing from fortune on Justinian. This likely came because China was still in a state of internal weakness, over three centuries after the Han Dynasty fell. This misfortune for China would prove fortunate for the Roman Emperor. To sum up, no one else was in a better position to steal this great trade secret than these monks.

Justinian took the opportunity and sponsored their mission, giving them whatever resources they needed to pull it off. Even with the emperor’s support, it would be a daunting challenge.

The Journey

The dates of the journey are unclear, but it took two years between 552 and 563.

We also do not have details on how, exactly, the journey played out. Because the monks would have needed to avoid Persian agents, most historians believe they took the northerly route, through the Black Sea, the caucuses, the northern part of the Caspian Sea, the steppe, the Gobi Desert, and ultimately on to China.

There, the monks would have needed to get hold of two things – silkworm eggs and/or larvae and mulberry plants for them to feed on. Then they would need to smuggle them out of China and back across the northerly route, avoiding bandits and other bad actors.

In China, the monks probably received potted mulberry bushes as gifts. Most famously, it is speculated that they hid the eggs or larvae of the worms in their canes as they made their way out.

Throughout the journey, their contacts in the Nestorian Church paid off. There is no way that the monks could have carried out this operation without such assistance along the route from Constantinople to China.

Everything succeeded, as the monks brought enough worms and mulberries back to the Roman Empire to create a viable, reproducing population.

Triumph of The Roman Silk Trade

Justinian Steals Silk

Justinian handsomely rewarded the monks. Afterward, he established factories throughout the Roman Empire. The most important one came at Morea in Greece. The emperor did not live long enough to see it flourish. Yet, by stealing silk from China, Justinian accomplished two vital strategic goals for the Roman Empire.

First, he had cut out the Persians from the trade. The Romans would no longer be financing their enemies. Second, he established a domestic industry which would prove a great source of revenue. Exports to Western Europe and elsewhere lined the imperial coffers. It was among the reasons the Roman Empire of the East lasted so long, despite massive military reverses in the centuries after Justinian.

Wits, bravery, and vision change history. This is the lesson of Justinian and his industrial espionage operation. We should remember it as China steals from us.

For more stories of historical wits, bravery, and vision, read Lives of the Luminaries, and subscribe to my critical battles series on Patreon.

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