In the middle of the sixth century, Emperor Justinian wanted the eastern Roman Empire to make its own raw silk. Roman craftsmen could already weave splendid silk cloth, but the material they worked with came from abroad, often through merchants linked to the rival Sasanian Persian Empire. Even skilled Roman workshops depended on traders bringing that thread from Asia, because the empire had no established supply from its own silkworms.
The historian Procopius records an attempt to obtain silkworms for the empire. Monks familiar with silk production in Asia offered to bring Justinian the eggs of silkworms. Eggs could be carried much farther than caterpillars that needed constant feeding. If the travellers could deliver them alive and arrange for the newly hatched worms to eat mulberry leaves, Roman territory might begin producing its own silk fibre.
The story is often illustrated with monks smuggling eggs inside bamboo canes. Yet Procopius never mentions those canes, and another late antique account makes the carrier a Persian visitor rather than a group of monks. Nor can we establish that the arrival of eggs immediately gave Byzantium an independent silk industry. These accounts describe the arrival of silkworm-rearing knowledge, but say little about the scale of the industry that followed.
Why silk mattered to Justinian
Long before Justinian took the throne in 527, Mediterranean buyers valued silk for its fineness and price. Merchants supplied the Roman world with finished fabric and raw thread, sometimes through several successive markets. Roman workshops could dye, pattern and weave that imported material. They did not necessarily practise sericulture, the breeding of silk moths and the harvesting of fibre from their cocoons. A city could make fine silk garments while remaining wholly dependent on distant farms for its raw material.
Silk suited the needs of an imperial court. Light enough to transport but expensive enough to impress, it could be given to foreign rulers, used in churches or made into clothing for the wealthy. Dyed and patterned silks, especially cloth associated with imperial purple, could help distinguish rank. Neither costly dyes nor skilled weaving secured the supply of raw fibre. That supply still depended on access to foreign markets and the political conditions along the routes linking them.
For Justinian, relations with Persia made that dependence particularly awkward. The eastern Roman state, commonly called the Byzantine Empire by modern historians, fought repeated wars with the Sasanian Persians. Their rivalry stretched across the lands from Mesopotamia toward the Caucasus, where commercial routes crossed disputed territories. Persia was one intermediary among several in a broad Eurasian silk trade, but an especially difficult one for a Roman emperor at war with it. In Justinian’s Wars, Procopius says Justinian wanted his subjects to stop buying silk from the Persians.
Procopius also describes the damage that changes in silk prices and taxes could cause to manufacturers. In his fiercely anti-Justinian Secret History, chapter 25, Procopius describes established silk garment makers in Berytus (modern Beirut) and Tyre. He blames higher Persian prices and Roman customs duties for damaging their business, then criticises a maximum price imposed by Justinian. The account is an accusation by a hostile author, so its picture of government misconduct needs to be treated cautiously. His complaints place the effects of imperial silk policy among merchants and artisans as well as at court.
Raising silkworms within the empire might have reduced the need to buy imported fibre and improved Justinian’s position in negotiations. Obtaining the eggs would still leave much of the work to be done. Breeders needed suitable mulberry trees, experience in keeping the eggs and larvae alive, people to handle the cocoons and artisans to turn the resulting fibre into cloth. Eggs alone could not establish that entire chain of production.
The monks who offered Justinian silkworm eggs
The fullest near-contemporary account appears in Procopius, Wars 8.17.1–8, where Procopius places the incident within his narrative of Roman dealings with Persia. He says that monks who came from India approached Justinian after learning of his desire to avoid buying silk from the Persians. They had, they explained, spent many years in a place called Serinda and knew a way for the Romans to produce silk for themselves.
Justinian asked the travellers how they intended to do it. According to Procopius, the monks explained that silk came from insects which were difficult to transport over long distances while alive. Their eggs would travel more easily. After being kept warm long enough, the eggs would hatch, leaving the new larvae to feed on mulberry leaves. Procopius specifies how the monks proposed to warm the eggs: they would cover them with dung.
Justinian offered rewards and urged the monks to carry out the plan. They went back to Serinda, obtained eggs and returned with them to Constantinople. Procopius says they raised the silkworms successfully and that silk could thereafter be produced in Roman lands. He gives no names for the monks and no itinerary for their return journey. Their denomination, the payment they received and the precise place where they collected the eggs are also unrecorded. There is no mention of hiding the cargo in walking sticks.
Later retellings often blur the differences between the surviving accounts. The monks, their return to Serinda, the eggs kept warm in dung and the emperor’s promised reward all belong to Procopius’s version. The hollow stem comes from a different author. The frequently repeated date of 552 is likewise an estimate derived from the historical context, rather than an exact year supplied in the passage. Justinian died in 565, and a date around the middle of the sixth century is as precise as this evidence permits.
Procopius ends his story once the worms have been raised. He does not explain who cared for them or how production continued. In practice, breeders would have needed to identify viable eggs, time the hatching and bring fresh mulberry leaves to the feeding larvae. The next generation would require breeding moths and enough surviving eggs for another season. One harvest might show that the method worked without proving that an established industry had taken root.
A different account names a Persian, not monks
The other late antique account reaches us indirectly. The historian Theophanes of Byzantium wrote during the later sixth century, but his history is now lost apart from material preserved by later authors. The ninth-century scholar Photios summarized that history, and the entry for Theophanes of Byzantium in Bibliotheca, codex 64 preserves his account. Theophanes’s account survives here only through Photios’s summary, which limits how confidently its precise wording can be reconstructed.
Here the person who brought the eggs is a Persian, coming from the land of the Seres. He carried them in a hollow plant stem to Constantinople and put them on mulberry leaves in spring, showing how the insects could be reared. Photios’s summary says that the insects later developed wings. It also relates that Justin II, who succeeded Justinian, showed visiting Turks the process of making silk. In this version, knowledge of silkworm breeding appears in a diplomatic setting after the original transfer.
The two authors agree on eggs brought west, the importance of mulberry leaves and the possibility of raising the insects in the empire. They disagree about who carried them. Procopius’s monks travel back to Serinda; the visitor described by Theophanes through Photios is Persian and comes from the land of the Seres. The hollow stem is found only in the latter story. Combining the monks and the stem into a single supposedly eyewitness description obscures that disagreement.
We cannot tell whether the different stories refer to separate journeys, different parts of the same transfer or an altered tradition about one event. Neither surviving account settles the question. Procopius also gives no basis for calling his travellers ‘Nestorian monks’, although that description is common in popular retellings. Neither narrative says that the eggs were stolen from China. They record no raid, arrest, identified Chinese victim or precise border crossing where eggs were taken.
Both accounts place knowledge of silkworm breeding in the Roman capital by the sixth century. The writers understood that silkworm eggs could be transported, hatched and used to begin raising moths on mulberry leaves. That is historically consequential even though the identity of the travellers, the route and the scale of production remain uncertain.
How eggs could become silk
The domesticated silkworm, Bombyx mori, begins as an egg and hatches into a larva that feeds heavily on mulberry leaves. Before changing into a moth, the larva spins a cocoon from a long protein filament. Silk production requires people to manage these stages and recover usable fibre from the cocoon. The timing of the life cycle, the temperature around the eggs and the availability of leaves all affect whether a harvest is possible.
For travellers crossing much of Asia, eggs were a more manageable cargo than larvae. They were small, and while dormant they did not require the continuous supply of mulberry leaves needed by feeding caterpillars. But a journey could still fail. If the eggs were exposed to damaging heat or damp, or began hatching before the travellers could feed the larvae, the insects would be lost. Procopius’s reference to warming the eggs after arrival describes a practical difficulty that the breeders would have had to solve.
Harvesting the cocoons introduced another choice. If an adult moth emerges naturally, it breaks through the cocoon and disrupts the continuous filament. The opened material can still be made into silk floss and spun, though it cannot be reeled as one long thread in the way an intact cocoon can. Many forms of silk reeling prevent the moth’s emergence by killing the pupa first. These different methods affect the character of the fibre available to weavers.
That distinction has influenced recent interpretations of the Persian visitor’s story. Historian Gang Wu’s 2024 study of Byzantine sericulture argues that Theophanes’s mention of winged moths points to a technique in which the insects were allowed to emerge and the pierced cocoons were later spun. The suggestion helps make sense of the ancient wording, but Photios’s brief summary is not a technical manual. It gives us neither the yield of the first harvest nor reliable information about the quality of the resulting fibre compared with imported reeled silk.
Silkworms could have been raised in Roman territory while the empire continued importing silk. Raising moths, extracting fibre and weaving high-quality textiles required related but different kinds of skill. The accomplished Byzantine fabrics surviving from later centuries show what weavers could do. On their own they cannot establish where the silkworms supplying their yarn were bred.
Where did the eggs come from: China, Serinda or Khotan?
Sericulture first developed in China, and people gradually carried domesticated mulberry silkworms into other parts of Asia. The place-names in the Byzantine accounts leave the starting point of the sixth-century journey uncertain. Procopius calls the country Serinda; Theophanes speaks of the Seres. Late antique writers could use such names for distant silk-producing lands without defining borders that can be mapped neatly onto modern states.
By Justinian’s reign, the oases of Central Asia were more than stopping places for merchants carrying Chinese silk. They contained farming communities and rulers who handled silk and, in some places, bred the insects themselves. Khotan stood on the southern edge of the Tarim Basin and had developed its own tradition of silk production before the sixth century. A traveller who learned to rear silkworms or obtained eggs there would not have needed to journey into the Chinese imperial heartland.
One Khotanese story describes a transfer of the same knowledge. The seventh-century Buddhist pilgrim Xuanzang wrote that a princess entering Khotan concealed silkworm eggs and mulberry seeds in her headdress. A painted wooden panel discovered at Dandan-Uiliq, now British Museum object 1907,1111.73, shows an elaborately dressed woman with attendants, cocoons and weaving equipment. Scholars relate its imagery to the princess tradition. The panel preserves the princess tradition in Khotanese imagery, but cannot independently establish the details of the earlier journey.
The princess and the monks also occupy different places in their respective stories. She is said to bring silk production into a kingdom by crossing a border to join a royal household. Procopius’s travellers offer their knowledge and eggs to an emperor who wants an alternative supply. Both traditions explain how a valuable technology might travel with a small, portable cargo and the people who knew how to use it. That similarity is illuminating, but it cannot establish that either journey happened in exactly the form later narrated.
There is stronger evidence that Khotan bred silkworms than there is for the princess’s particular journey. Archaeologists have found pierced cocoons and spun silk, material consistent with moths being allowed to emerge before the fibre was worked. Xuanzang also describes a ban on killing silkworms, a practice that would favour this method. Wu draws a comparison between such evidence and the moths with wings and dung-warmed eggs in the Byzantine accounts. He concludes that Khotan, or another nearby oasis, is the most likely immediate source of the technique described by the Roman authors.
Wu’s argument makes Khotan a plausible intermediary without identifying the journey taken by Procopius’s monks. We have no recovered itinerary for Procopius’s monks, and the name Serinda cannot by itself fix their destination. The breeding practice ultimately came from China and may well have reached Byzantium through regions that had already adapted it. Khotan remains an especially strong candidate within that wider history, but the evidence does not prove it was where the eggs for Justinian were collected.
Persian trade, imperial workshops and the limits of a silk monopoly
Even if the first eggs arrived and hatched successfully, the imperial government’s efforts to control the silk trade did not end. In the Secret History, Procopius accuses the financial official Peter Barsymes of forcing silk workers into an imperial operation and charging excessive prices, particularly for imperial purple dye. His account is written in anger against Justinian’s administration, and its charges cannot be treated as an impartial record of every sale. The accusations reveal disputes over taxes, labour and the price of luxury silk within the imperial economy.
The imperial government had financial as well as ceremonial interests in the trade. Elaborately patterned textiles and purple clothing helped communicate authority; silk was also a gift suited to rulers and religious foundations. Imperial control over particular workshops or sales did not necessarily extend to the entire silk trade. Sericulture, spinning, weaving, dyeing and the import of cloth or thread could involve different producers. An imperial monopoly in one part of the market would not necessarily give the treasury command of them all.
The Metropolitan Museum’s account of Byzantine woven silk describes Byzantine workshops producing fine fabrics from imported silk before domestic breeding was securely established. An example of the craft is the Dumbarton Oaks ‘Hero and Lion’ silk, dated broadly between the seventh and ninth centuries. Its complex woven imagery demonstrates the skill of the makers, but the textile cannot tell us where the worms producing its fibre lived. Finished cloth can be strong evidence for textile manufacture while remaining silent about the farms and merchants supplying its raw material.
Foreign trade continued to be a political concern after Justinian died. In 568 a Turkic embassy linked to Sogdian merchants arrived at the court of Justin II. The visitors sought commercial and diplomatic ties that offered ways around Persian intermediaries, and a Roman embassy followed. Accounts of Menander Protector, examined in an annotated translation of the 568 embassy, preserve the episode. These negotiations are difficult to explain if one delivery of silkworm eggs had already made access to Central Asian silk unimportant.
Silk merchants used changing routes through several states, rather than one fixed road across Asia. Persian influence and Turkic control in Central Asia changed, new powers entered the trade, and shipments could include either raw thread or woven fabrics. Routes and intermediaries varied. A story in which Byzantium suddenly broke a complete Chinese monopoly by smuggling away a few eggs leaves out most of this political and commercial complexity.
Did Byzantium establish its own silk industry in the sixth century?
Procopius’s account ends with silk production becoming possible on Roman soil. He does not tell us how many rearers worked there afterwards, how much fibre they produced or whether their operations survived for generations. Records of sericulture in Byzantine territory are sparse from the sixth through the eleventh centuries. An initial hatching could be remembered in a written story without leaving the traces that a widespread system of productive farms might leave behind.
Wu has argued that secure evidence for a well-established Byzantine sericulture industry does not appear before the eleventh century. Raw silk imports remained important at least into the tenth. Those facts cannot show that Justinian’s first silkworms necessarily died out, and they certainly do not erase the evidence of earlier Byzantine weaving. They indicate that our knowledge of domestic breeding is far more limited than our knowledge of the fine textiles made or used in the empire.
A silk fabric passes through several stages before anyone wears it. Mulberry trees must provide leaves; rearers must care for eggs and larvae; someone must work the cocoons into filament or floss; spinners and reelers prepare yarn; weavers, dyers and finishers produce cloth suitable for sale or ceremony. Different places could specialise in different stages. Archaeologists who recover an accomplished Byzantine textile may identify traditions of weaving or design, but cannot locate the original mulberry groves simply by looking at the cloth.
Some local production may also have yielded fibre that competed poorly with imported silk. Wu suggests that the Khotanese practice of allowing moths to emerge produced pierced cocoons and silk that required more labour to spin than the long reeled filament used in costly textiles. That might help explain why imports continued alongside knowledge of breeding. It remains a hypothesis: the sources do not preserve enough evidence to calculate costs, output and prices across the sixth-century silk economy.
Later Byzantine writers provide evidence that silkworm-rearing methods continued to change. Michael of Ephesus, writing in the twelfth century, and Manuel Philes, writing in the late thirteenth and early fourteenth, discussed the silkworm’s life cycle and methods of heating eggs. Their descriptions suggest familiarity with moths emerging from cocoons, even though the means of warming eggs no longer matched Procopius’s dung-covered method. They offer glimpses of techniques developed and adjusted over centuries, rather than a single unchanging procedure brought by sixth-century travellers.
The silk that survived: from Justinian to medieval Constantinople
By the Middle Ages, silk woven in Byzantine centres had become highly valued throughout the Mediterranean. The surviving pieces display accomplished pattern work and colour, and many were used for church furnishings or imperial ceremony. The prestige of Byzantine silk helped keep the story of Justinian and the silkworm eggs in circulation. It appears to give one memorable beginning to a trade and craft whose products travelled far beyond the capital.
The Bamberg Gunthertuch, a large silk hanging associated with an emperor of the tenth century, shows the later reach of that production. Its design presents a mounted ruler beside female personifications of imperial triumph. Bishop Gunther of Bamberg acquired the fabric on a journey in 1064–65; after his death it was placed in his tomb and later recovered. The hanging tells us a great deal about luxury weaving and the use of imperial imagery, though nothing directly about the handling of silkworm eggs or cocoons.
Surviving silks such as the Gunthertuch can sometimes be connected with particular artistic traditions or centres of manufacture. They are much less revealing about the earlier stages of supply. A cloth kept in a church treasury or used in a bishop’s burial has a documented life as a prestigious object, but the route taken by its raw fibre may remain unknown. The history of Byzantine textile making and the history of Byzantine silkworm farming cannot be read as one continuous record.
The image of monks arriving with eggs belongs to a much later visual tradition. A late-sixteenth-century engraving in the Metropolitan Museum of Art shows Justinian receiving eggs in a tube. Made about a thousand years after the supposed transfer, it illustrates how early modern artists understood the tale. It provides no independent evidence for the appearance of the travellers or the way the delivery took place in the emperor’s court.
The surviving evidence begins with two different late antique reports: one describes monks bringing eggs to Justinian and successfully raising silkworms on mulberry leaves, while the other credits a Persian traveller with the transfer. Neither account reveals exactly how large or lasting the first Roman production became. Imports and diplomacy with Persian and Central Asian trading powers continued, and Byzantine methods developed over many centuries. Transporting viable eggs could make local breeding possible, but developing a substantial silk supply involved many further stages that the sixth-century accounts do not document.
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