Galactic Map

Map of the Altarion Empire
(Click to enlarge)

Some useful details:
Solarian Kingdom (Earth) is marked in yellow.
Its allies Theitor and Anthira are green.
Aggressive kingdoms/enemies are red.
Areas marked in pink are neutral or friendly.
There are two blue dots: Anthalia is the star system of planet Anthalanor,
the Second Empire capital. 
Amathial is the ancient capital, and the home planet of the Taladaar and Emperor Shaix.
The fifty major domains marked in this map are entitled to a spokesperson in the Altarion Council,
but they also represent some of the surrounding minor realms. Buffer states abound. There
are also sectors that left the Empire, or never rejoined after the war. Those can be isolated,
peaceful planets or pirates and outlaws hideouts.
About the Void Barrier:
My spaceships work with a variant of the Alderson drive (called "Shaix Drive" in-universe): they latch to the entry points of natural wormholes (or "leys"). Each ley only connects, instantly, two gates in space. They can be in the same system, or at the far ends of the galaxy, so star navigation is rather non-linear. Known leys big enough for starships have been marked with satellite rings. Interstellar/interplanetary communication stations are usually placed near the gates. Moreover, they are fractal in nature, so each "major" ley usually has lesser branches that connect all the planets in the system. They're often too small for starships, but useful for communication.
The Void Barrier surrounds the inner section of the galaxy, because (apparently) all the leys connecting it to the other sectors collapsed as a consequence of the Taladaar War. That event happened more than 10,000 years in the past and marked the end of the First Empire.