The term "galactic community" is a phrase that can refer to either:
The galactic community grew with the growth of technology and discovery of new systems and civilizations. The first notion of galactic community can be considered the Infinite Empire. With the passing of time, more of them joined or began interaction with the growing Galactic Republic.
Isolated or undiscovered locations, species and civilizations were not part of the larger galactic community. For example, the Republic and the Sith Empire were unaware of the existence of each other, until the Great Hyperspace War and the fall of the Empire shortly thereafter.
The Unknown Regions were those regions of the galaxy that were not part of the wider galactic community.
The concept of galactic community is similar to the real-world's international community.
The concept of galactic community is similar to the real-world's international community.