The Old Republic
The governmental organization known as the “Old Republic” refers to the first established galactic political body in the universe. This Republic was formed amidst battles with many various governments and factions in galaxy, including the Mandalorian and Sith Empires.
The Republic was based on Coruscant and saw the Jedi Order as its ally. Though not part of the Republic, the Jedi Order was an autonomous organization that assisted the Republic when called upon, usually in response to threats from the Sith Empire. The Jedi Order, being a separate organization, was based off of the planet Tython.
The days of the Old Republic ended when the Jedi and Republic forces united to battle the Sith Empire a millennium ago. In a series of large scale military operations, in a number of theatres of war across the galaxy, the combined forces of the Jedi and Grand Army of the Republic struck decisive blows to the Sith Empire, scattering or capturing their soldiers, and slaying the Dark Side using Sith Masters and Apprentices in what was to be known as the Great Sith War. As the last Sith fell, the Old Republic and Jedi Order were joined and restructured into the first Galactic Republic.