A long-term accomplishment of Justinian was the establishment of silk production in the Roman Empire ...

A long-term accomplishment of Justinian was the establishment of silk production in the Roman Empire “in a fascinating tale of industrial espionage” whereby monks acting as imperial agents “managed to acquire the secret of silk production” & smuggle them back in bamboo canes

The monopoly in Eastern Asia on Silk  production was a net economic loss for the Romans. Gold flowed out and all the empire got back was silk, it crucially also enriched their rival Persia. According to Procopius the smuggling from the East took place in the early 550’s, when “silkworm eggs had been smuggled into the empire by eastern monks employed for that purpose on Justinian’s behalf. Procopius records that, ‘at about this time, certain monks coming from India, and learning that the emperor Justinian entertained the desire that the Romans should no longer purchase their silk from the Persians, came before the emperor and promoted to settle the silk question….for they had learned accurately by what means it was possible for silk to be produced in the lands of the Romans.’”

Their motivation was simple - Justinian “‘had promised to reward them with large gifts,’ and as a result they made their way to the land ‘situated north of the numerous nations of India’ and smuggled back silkworm eggs feeding on mulberry leaves.” The benefits for the Romans were clear to see “when in the 560’s the Turks offered to sell raw silk directly to the Romans, obviating the Persians (with whom they had fallen out), they were horrified to discover that the imperial authorities were not interested.” For the Romans now had the secret themselves.

From that point on, silk production in the Roman Empire later “would form an important part of the empire’s economic arsenal, as traders from throughout Europe flocked to Constantinople in pursuit of this precious commodity.” Constantinople now had its own valuable export. This was an extremely profitable investment for the Roman state

Source - Justinian: Emperor, Soldier, Saint by Peter Sarris @peter_sarris