Astrography and Astropolitics

Human Space is about 400 parsecs across and is divided up into nine administrative zones, called (somewhat inaccurately) 'Quadrants'.

The eponymous Quadrant Zero is the central quadrant, wherein lies Earth - the home of humanity and all the oldest colonised worlds, the 'Home Worlds'.

Around Quadrant Zero are eight other quadrants, numbered 1 to 8. These contain the colonial worlds - frontier worlds that are, on the whole, much less developed that those of Quadrant Zero.
If it helps, think of them as 'wild west frontier' type worlds.

Communication and travel times between the outer quadrants and Quadrant Zero are measured in months - so all polities with an interest in the outer quadrants maintain separate arms of government in each quadrant - headed by a Governor (or the equivalent).
Each polity in each outer quadrant will have its own seat of government, its own fleet etc.
There is often a tension between the Governors and the Home Worlds, and, more importantly, it is the nature of conditions in the outer quadrants that local tensions flare up into military action or sometimes even war.
In many cases these 'little wars' are over and resolved before the Home Worlds even hear about it.

In other cases, the political fallout from such a conflict can spill over into Quadrant Zero.