The Perseus Arm, Sagittarius Arm, Cygnus Arm, Scutum Arm, and Orion Arm were the Milky Way's five major spiral arms.
Although the Orion Arm was the smallest, it was not merely a minor arm as Earthlings imagined. It too originated at the galactic center.
Each of the five spiral arms was divided into an upper, middle, and lower reach, followed by its outer tip.
Each section was divided into five celestial sectors, with anywhere from one billion to ten billion stars in each sector.
That made a total of one hundred celestial sectors and nearly three hundred billion stars.
Notably, the Milky Way Galaxy's main cradles of life lay only in the middle and lower reaches of its spiral arms. The upper reaches, too close to the galactic center, and the outer tips, too far away, contained almost no places where life arose naturally.
If all these cradles were illuminated, they would form a ring, precisely covering the band at the Milky Way's golden ratio.
This annular region was called the Life Source Ring.
Of course, that did not mean life could never arise outside the ring. The probability was simply extremely low.
A full 99.99 percent of life originated within the Life Source Ring. This was a statistical result, an observed phenomenon. The civilizations had yet to agree on an explanation.
In short, this meant many celestial sectors had no indigenous life at all. They consisted entirely of colonized regions.
The regions near the galactic center comprised the twenty-five great upper-reach sectors.
All twenty-five belonged to the Star Alliance, under the lofty designation of "the shared wealth of all intelligent beings in the Milky Way."
Of course, through the Galaxy Battle Tournament, Virtual Universe wars, and other means, every civilization was eligible to gradually claim a share of them.