Since the early times food was enriched to have more taste.
The ancient Romans had the garum. The sauce was generally made through the crushing and fermentation in brine of the innards of various fish such as tuna, eel, and others.
The medieval times in Italy saw large use of ghiotta which is a sauce that includes red wine, oil, bacon or ham, capers, vinegar, olives, anchovies, onion, garlic, cloves and/or juniper berry, sage and lemon juice.
The discovery of America brought a revolution on European tables with a lot of new ingredients. It took centuries before these ingredients from the new world were largely used for sauce ingredients in Italy, but we eventually had the triumph of the tomato.
Follow the links to see how to prepare the sauces of actual Italian modern cuisine.