As the name suggests, Porchetta (Roasted Pork) derives from pork. Pig breeding in Italy has always been very important and its development follows human evolution, since the time of the Etruscans.
The Romans also cooked and loved this type of meat. They are the ones who handed down to us the “Porcellum farcilem”, a recipe with pork very close to the Porchetta that we still eat today. The Apicius cookbook includes this recipe, for this reason it is very likely that the origin is from central Italy.