What are the PoDs necessary for something like this? I was thinking, if competition is the problem, then in East Asia you can have China split into something like 8 states and then remain separated, or just butterflie it's initial unification.
In Europe you could prevent the collapse of the unified Roman Empire, so it is still considered paramount to civilization itself, and there is no need to do much else; external invaders such as the huns or german peoples chosing instead to become emperors using the existing system rather than displace it, causing the borders to remain mostly static and the technology to regress constantly, until finally the continent is forcefully opened by chinese and japanese gunboats in the 17th to 19th centuries, after having discovered the Americas some centuries earlier trying to get to the west through sailing into the east.