The future is a dangerous place for mankind.
Humanity has spread through to the stars. After a bloody civil war, the Terran Empire has broken into several different factions, which have been involved in low level conflict ever since. Humanity as a whole has since occupied most of the Orion Arm, and there are countless empires and factions working even beyond their own borders.
The Terran Empire is a tightly controlled political body based on the principles of a constitutional monarchy, with highly exaggerated executive powers rested upon the monarch. While it is possible for the legislative bodies of the Empire to govern against the will of the Emperor, in practice it is highly difficult to do so due to the personal powers vested in him. The Empire enjoys a significant military-industrial complex, as it's territories were among the first to be colonized by humanity.
The Vela Republic is a loose association of planets bound together more by the need for common defence than any social, political or economic factors. Many of it's planets are self sufficient, and would otherwise be neutral, independent and uninvolved in outside conflicts if given the opportunity. While lacking in centralized shipbuilding and defensive nodes, they do enjoy the advantage of having a diffuse collective economy, that would remain largely unaffected by the blockade or invasion of any specific planet.
Once a galaxy-spanning empire, the Drae Remnants are now just a shadow of their former strength. Torn apart and weakened by centuries of civil war, they found themselves extremely vulnerable to the uprisings of many of their former subject species. While much of the Drae have found it expedient to integrate itself into other factions, some of their more powerful planets have forged small empires of their own.