All of those things were taken well after any reasonable patent would have expired, so I don’t think they are comparable to the ip theft currently being discussed in this thread. I thought the upstream comment was talking about more recent examples.
Did China try to prevent gunpowder or porcelain from being made by outsiders?
They definitely did try to keep porcelain a secret. As of gunpowder it wasn't stolen by Europeans, rather it seems that it was Mongol invasion that let the knowledge spread.
> All of those things were taken well after any reasonable patent would have expired, so I don’t think they are comparable to the ip theft currently being discussed in this thread.
"IP" is broader than patents that tend to have an expiry date - but even the expiration periods of patents is determined by the host government and not the appropriator. The US has a lot of classified information that would have long since expired had it been a patent, e.g. 1970's nuclear tech, alloys used in submarines, stealth coating on jets. Porcelain and the other examples gp gave would have fallen under the blanket of "National Security" rather than patents.
Did China try to prevent gunpowder or porcelain from being made by outsiders?