These "accidents of activity" doesn't flow one way either. Just like Italy influences, it has been enormously influenced and impacted by other nations as well. You can't exist for 2500 years and not be impacted by other civilizations during that time. All nations learn from one another. Especially Italy with its long, tortured, sometimes parochial, glorious past replete with successes of empire and failures of national unity. It has been invaded so many times, it's hard to pinpoint how many customs and ideas their borrowed.
Constantino Brumidi who was, for a time, the forgotten artist behind the fresco work at the Capital Building in Washington, D.C., one is reminded the exchange of ideas mentioned earlier never stops.
More poignantly, the legacy of inspiration they leave behind eventually does get rediscovered as was the case with Brumidi who was largely an obscure figure until the determined Myrtle Cheney Murdock found out who the artist behind the Capitol art (including the Brumidi Corridors) was.
Next time you dismiss an artist as being paranoid for fear of becoming forgotten, think of Brumidi.