Complex sentence: Following conquest by the Frankish Empire, the title of King of Italy merged with the office of Holy Roman Emperor but as an absentee foreigner who had little concern for the governance of Italy as a state, Italy gradually developed into a system of city-states.
Split into simpler sentences: Following conquest by the Frankish Empire, the title of King of Italy merged with the office of Holy Roman Emperor. However, the emperor was an absentee foreigner who had little concern for the governance of Italy as a state; as a result, Italy gradually developed into a system of city-states.