The galaxy is one of the billions of galaxies in the Known Universe, consisting of 400 billion stars and 180 billion star systems in 120,000 light years. There are as many as 20,000,000 sentient species in the galaxy, which has had a complex history of diplomacy, trade, travel, politics, and war that has seen much destruction and interaction between the species. The galaxy was first united under the Galactic Republic, and it was later ruled by the Galactic Empire, New Republic, and the Galactic Alliance. It saw the Jedi and Sith, users of opposite sides of the Force, fight each other for thousands of years, with the Jedi being the preservers of truth and friendship while the Sith were greedy and violent. The galaxy also saw great wars such as the Great Galactic War, Clone Wars, Galactic Civil War, and the Yuuzhan Vong War, the last of which involved invaders from another galaxy attacking the galaxy. Although there was much warfare and violence in the galaxy, it always recovered, surviving millenia of conflict.