Greeks founded many of the colonies in southern Italy and Sicily many centuries ago. About the same time, the Etruscan civilizations were developing in the north and central regions of what is now Italy. Another geographic line is the veal line. This line, just south of Florence, separates the lush pasture lands of the north from the poor grazing lands of the south. Where those ingredients aren't available in the south, cooks must make do with other ingredients.
Pastas are also different in the north and south.
Pastas in the north usually contain egg, and the sauces are more delicate. In the south, the pastas are made with just flour and water, so the sauces must be stronger because the pasta is harder. This is the land of Barolo wine and truffles. Risotto or rice dishes are another specialty, often covered with truffles. The cooking is dense, and flavors and aromas result from combinations rather then mixtures.