Why was the italian peninsula divided ap euro?

After the fall of the Western Roman Empire, and the rise of Feudalism, many different Kingdoms were established. Other parts were ruled by the Byzantines, The Holy Roman Empire, and various city states. However, after the Italian Wars, (Which rose from disputes over the Duchy of Milan and the Kingdom of Naples, later the wars rapidly became a general struggle for power and territory among world powers, and were marked with an increasing number of alliances, counter-alliances, and betrayals) The victors took territories

that they had "won" during the wars.