The Old Empire was the name of the Space country who's name is lost to history that was based on planet Earth and all of the colonies withing about 100 light year radius but had exploration though out the local Quadrant or Sub Galactic sector which ever the case may be.
But regardless of whatever this countries true name might it have been the alliance of free stars or Earth Alliance , Terran Confederation or what ever is unknown. At some point in the late 21st century the planet had become mostly politically united. From about 2100 AD the discovery of Warp speed technology began around this time by using a crystaline mineral known as Endurium that was first discovered on the planet Mars. Its remains unclear how many alien races might have resided in the Old Empire, but what is clear is that the Earthlings were the most dominant and well documented race in its sphere of influence on the local star map. Around 3478 the Old Empire came to a end.