Original: The republican period of Ancient Rome began with the overthrow of the Monarchy c. 509 BC and lasted over 450 years until its subversion , through a series of civil wars , into the Principate form of government and the Imperial period .
Simplified: The republican period of Ancient Rome began with the overthrow of the Monarchy at about 509 BC and lasted over 450 years until its subversion , through a series of civil wars and the Imperial period .