Probably any empire serves as an aggregator, innovator and purveyor of knowledge. Peoples on the periphery of an empire would be involved with it and so acquiring and passing knowledge. The ending of an empire would then isolate the peoples it had connected.
Or so it seems to me.
Add to that the fact that lanes follow animal trails, roads follow lanes, avenues connect lanes or simply increase their capacity....and:
Eventually, a druid road can easily become a roman road.
Or, Route 66 becomes a side note to the interstate system.
Generations add techniques and/or specialization (skids vs two wheels vs four wheels, etc.)...
Purpose pretty much remains the same.
Try walking across a hill 1n Germany, and see how much the language changes. Until the Duden, the Germans could not even talk to each other.
“Neanderthal” means from the next vally, you know.
I agree.
The main problem the Romans had was internecine warfare. The Empire spent much of the third century engaged in civil wars between a patchwork of quasi-imperial pretender states. And it still endured. My favorite of the 3rd c emperors is Aurelian — had some crook on his staff not murdered him, he’d have been better remembered for the things he never got to do as a consequence (whatever those would have been).
During his five year reign he defeated (basically destroyed, in some cases) invading barbarians, reunified the empire, built the city wall around Rome, and abandoned Dacia which was n of the Danube, hard to defend, and probably well-stripped of wealth by his predecessors. The conquest of Dacia by Trajan during the 2nd c had marked the economic high point of the old empire, but those days were behind it.
http://en.wikipedia.org/wiki/Aurelian
Good comment and accurate. Then that same empire eventually calcifies losing its dynamism and the benefits of aggregation/dissemination pass to another. Isn’t that history?