For a very long time the Roman empire was able to acquire silk through trade over 'the silk road' to China, but never able to unlock the secrets of producing it domestically themselves. Until 552AD, when two monks preaching in India then travelled to China, where they witnessed the guarded methods of using the live silk worm to spin the famous thread. Knowing the importance of what they'd learned, the monks returned to Constantinople to report directly to the emperor Justinian. He personally met the monks, heard all the details of what they'd seen, then asked them to return to China and find a way of smuggling these worms back to the empire. They agreed, and prepared for the 2 year ~6,500km (4,000mi) trek back to China on foot, hoof and wheel. Once back in China they acquired either eggs or young larvae, since the adults are too delicate for transport, and tucked them into hollowed bamboo canes for the long journey straight back home. Once the monks made it back to Constantinople (modern Istanbul, Turkey), domestic silk production slowly ramped up and the need for long journeys along the 'silk road' ramped down. Over time, this allowed the same type of silk monopoly which China had enjoyed through the prior centuries to now be established in the Mediterranean, becoming one of the bedrocks of the Byzantine economy for the next 700 years.
It's crazy to think about these two guys. 1500 years before you or I were born, making their second multi-year, 6,500km trek back from China, smuggling two bamboo canes full of bugs which would fuel the economy of one of the world's largest civilizations for the next 700 years. I wonder if they knew and understood these possibilities when they went to scoop the worms from their baskets in China...Imagine the anxiety trying to keep them hidden and alive the whole way back!