A system of government in which power is divided between a central authority and costituant political units...
First was the Roman Republic, then came the Roman Empire. In the 4th century BCE, the Roman Republic turned to imperialism. After losing a significant battle with the Gauls, a Celtic people, the Romans concluded that in order to sustain safety, they would have to expand their territory so the frontiers would be a good distance from the capital, Rome. They successfully fought a series of wars with other Italian city-states as well as the Carthaginians, achieving their goal. Warfare gave excessive power to the military leaders, weakening the influence of the Senate and thus the democracy became undermined. That is how it was transformed to a vast empire.
Answer:
That's where they were able to find the resources they needed for economic growth like minerals such as iron and gold. They didn't settle somewhere else because no other land had the resources they were looking for.
