The Infinite Empire was the first known major galactic government. It was founded by the Rakata, who by combining advanced technology and The Force, created technological wonders, including the Star Forge. They used the Star Forge's capabilities as a star ship manufacturing plant to control and enslave it's galactic neighbor's. At it's height of power the Empire included ten billion Rakata and over one trillion slaves. After a few millenia the Dark Side energies of the Star Forge corrupted its masters. The Empire fractured and the slaves revolted causing a massive civil war. A disease spread through the Rakata like wildfire and the population was decimated. Because of the disease they lose their connection to The Force.Those who weren't killed in civil war or killed by the disease retreated to their home world, Lehon. Those who retreated to Lehon soon discovered that because they could no longer use The Force they couldn't control their machines. The remaining Rakata would turn to cannibalism and barbarism. By the time Revan arrived in 3,959 BBY, all that remained were a bunch of primitive tribal groups.
The infinite empire expanded across many worlds and took many species as slaves. The head species who rules over this empire were the Rakata, a species who were uniquely in tune with The Force. Eventually, they would disappear, the empire would fall and many of the artifacts of the era would be hidden for many millenia.