Byzantium smuggled silkworm eggs to bypass Persian silk tolls

By the mid-6th century, Byzantium's silk came almost entirely from China, but every shipment had to cross Sassanid Persian territory, and Persia — a chronic Byzantine rival — used that chokepoint to impose steep tariffs on top of what Chinese producers already charged. Byzantium was paying a hostile power a toll on a good it couldn't source any other way, and no amount of trade negotiation with Persia could remove a markup Persia had every incentive to keep charging.

The conventional response to a hostile middleman is to negotiate for better terms or find an alternate route through the same chain of intermediaries. Emperor Justinian I instead backed a plan to bypass the entire chain: acquire the living organism China's silk monopoly actually depended on and grow silk domestically, eliminating both the Chinese supplier and the Persian toll booth in one move.

Around 552 CE, Nestorian monks acting with Justinian's backing traveled to Central Asia and China and smuggled silkworm eggs — or newly hatched larvae — out of the region concealed inside hollow bamboo canes packed with straw to keep them dormant during the journey, bypassing Persian-controlled trade routes entirely. Delivered alive to Constantinople, the eggs hatched and became the seed stock for an entirely new, domestically controlled Byzantine silk industry.

Smuggled silkworm eggs in hollow bamboo to acquire the means of production, bypassing the entire intermediary chain and eliminating Persia's structural leverage.

Smuggling eggs acquired the means of production, not just a product, eliminating the need for the entire trade chain.

Domestic silk production removed Persia's leverage, as tolls only applied to goods crossing its territory.

Even inferior early silk reduced spending on imports and tariffs, and the industry matured into a monopoly.

When a supplier has structural leverage, stop negotiating and acquire the means of production yourself, even if initial quality is lower.

Byzantium established its own silk production, centered on imperial workshops, sharply reducing its spending on imported Chinese silk and the Persian tariffs riding on top of it — though the early Byzantine product remained lower quality than genuine Chinese silk and did not eliminate the original trade outright. Byzantium nonetheless held a European silk-production monopoly for centuries afterward, until the knowledge and the worms themselves eventually spread further west.