After the kings
The Republic was launched in 509 BCE with a new political system, which included the Senate, people’s assembly, and two consuls. This was 250 years after the founding of the city, but few details from this period can be confirmed. We know that in 494 BCE, the Plebeians revolted, forcing the government to create a new magistrate position, the tribune, who would represent the plebeians. Later, in about 450 BCE, the plebeians forced the government to write down the laws of Rome (The Twelve Tables) and display them in the Forum for all to see.
The Romans went to war with the Etruscans in 405 BCE and it took them 10 years to capture the city of Veii. After many wars over many decades, the Romans defeated the Etruscans for the final time in 280 BCE, and absorbed Etruria into the republic.