We think of countries as having clear borders. In fact, borders are constantly changing, and what we think of as Europe's countries and boundaries are only moderately related to those of the Middle Ages.
Everyone knows where Italy is, that big boot-shaped peninsula sticking out into the Mediterranean. But where exactly are its northern boundaries? They are in the Alps somewhere, up in a region that is at least partially German-speaking. (When they found the Ice Man in a glacier, it was initially unclear whether he was in Austria or Italy.) Are Sardinia and Corsica part of Italy or not? (Corsica is now part of France). And how far around the Adriatic to the east does Italy go?
In the Middle Ages, Italy was not its own country, even though that big boot-shaped peninsula was known then as now as Italia. It had of course been the heart of the original Roman Empire, and its northern half (or so) had been part of Charlemagne's empire. As I discussed in my previous post on the Holy Roman Empire, from the tenth century on the western Empire was basically Germany and Italy.
German kings would be elected and crowned, then cross the Alps to be crowned emperor in Rome, beating up some Italians en route. Then they would go home again. This kept Italy from developing into its own kingdom, as France and England and even Germany were doing. Machiavelli in the sixteenth century deeply deplored this. In fact, Italy did not become a unified country until the nineteenth century.
When it was finally unified, there were a few bits never properly incorporated. Venice, which had been an independent state since its ninth-century foundation, was the last to join. San Marino is still a tiny, independent country completely surrounded by Italy. Vatican City is the largest and most important independent unit within Italy.
Sicily, the football at the toe of Italy's boot, had been a separate kingdom from the twelfth century. It is still looked on with suspicion by northern Italy.
Medieval Italy was the most urbanized part of Europe, with more cities (and bishoprics) per square mile than anywhere else. Its cities flourished as trade centers, for Italy was where the luxury goods of the East, the silk and spices, first reached Europe. Italian merchants understood capitalism, "Buy low, sell high," and had complicated business models to raise money by having people invest in merchant ships and cargo, essentially selling stock.
Initially the cities were all headed by elected city councils and usually a mayor; in effect, they were oligarchies, run by the rich merchant families. During the late Middle Ages and Renaissance, most cities were taken over by tyrants, men who seized power and didn't want to hear any opposing views. Florence was about the last to remain, at least nominally, a republic. Late medieval popes ran Rome and its surrounding region essentially as tyrants. (Click here for more on late medieval popes.)