I know how big the real galaxy is but,
they designated how far who goes where. Space filled up quick after all those series. I guess you can take it as the "faster than warp species" out of the galaxy.
All Star Trek maps are at best guesswork, but this one is simply wrong. As per First Contact, the Federation encompasses "8,000 light years"; the Milky Way galaxy is at least 100,000 light years in diameter. So the Federation can't be more than 1/10 of the galaxy (and probably quite less), while here it's at least half of the galaxy.
Also, no way the Kzinti/Tzenkethi and Talarians have a larger territory than the Cardassian Union.