What system of government did Rome exist under at its founding? What event caused the Romans to create a republic?

The Romans established a form of government - a republic - that was copied by countries for centuries In fact, the government of the United States is based partly on Rome's model. The ladder to political power in the Roman Senate was different for the wealthy patricians than for the lower-class plebeians. It all began when the Romans overthrew their Etruscan conquerors in 509 B. C. E. Centered north of Rome, the Etruscans had ruled over the Romans for hundreds of years. Once free, the Romans established a republic, a government in which citizens elected representatives to rule on their behalf