Answer:
Rome was headed by a King during the early years but changed to having consuls to govern them. They practice elections to select the rightful politician. The army protects the people and slaves wanted to have this protection through their masters. The Senate became powerful people that make decisions in Rome.
The middle age is governed by a monarchy. A lot of innovations and agricultural improvements had come in after the change. The king's army protected these people in exchange for land and taxes. Religion had been a powerful entity besides the King.