The Arbat Confederation is a group of stations composing of Kievskaya, its adjoining stations, and apparently at one time, Park Pobedy. The confederation is mentioned in the novelMetro 2033, but not in the video game.
The Arbat Confederation is a moderate capitalist autocracy (so to say) governed by Caucasians and non-Russian nationality traders. Besides a high number of Stalkers, little is known about this alliance. In the beginning, it had substantial power and population. During the Hansa-Red Line war it was allied with Hansa. Although they gained the station of Lenin Library (later given to Polis) they were severely weakened and the population decreased over the years. With the unseen threat from Park Pobedy to Kievskaya that was only disposed of in recent years, people have been fleeing the station, which led the Arbat confederation to install a soft quarantine regime on Kievskaya-radial (the blue line). Now the Arbat Confederation is nothing more than a weak Hansa satellite, dependant on their resources and protection.
Although it is never implied, it could be assumed they would be enemies with the Fourth Reich due to their high non-Russian population as well as their affiliation with Hansa, though their relative distance from Reich territory might mean the two factions are disinclined towards each other.