The quadrants main powers include the United Federation of Planets, Romulan Star Empire (and later the Romulan Republic) and Klingon Empire. Other smaller powers include the Orion Syndicate, Gorn Hegemony.
The Federation has maintained peace with the Klingons for nearly a hundred years, and has forged a stronger new alliance with them after the Dominion War.
As for the Romulans, their government was weakened by an attempted coup by the Reman Shinzon. Later, the star Hobus went supernova and destroyed their homeworld of Romulus. The former empire is now in ruins.
- Alpha Centaurans