The Gradin Belt is a region of the Delta Quadrant several thousand light-years in diameter approximately 40,000 light years from Federation space. It is connected to the Alpha Quadrant by the Barzan System (Alpha Quadrant) ninety-one days by way of the Barzan Wormhole. Of all of the areas in which Starfleet operates, this one is the most well-explored and well-studied. It is a confluence of many different advanced powers and so is currently a diplomatic hotbed.

History

Initial Discovery

In 2375, the USS Voyager first discovered the Gradin Belt when it passed through and destroyed a subspace vortex controlled by the Malon Cooperative. For the next fifteen months, it travelled through the Gradin Belt and made first contact with dozens of species including, most notably, the Devore Imperium, the Hierarchy, the Turei Alliance and the Vaadwaur. The USS Voyager departed the Gradin Belt in mid 2376 when it used a graviton catapult to shave three years off its return to home. Starfleet would not return to the Gradin Belt again for over a decade.

Rediscovery

In late 2388, researchers discovered an aperture for the wandering Barzan Wormhole in the Epatha System. While it was initially unstable, a science vessel was able to help stabilize this aperture of the wormhole, in combination with one in the Barzan system and another ship past the Nekrit Expanse. Presently, this connection allows supplies and ships to transit back and forth on a regular basis.

There are no major Starfleet facilities besides a relay station at the mouth of the Barzan Wormhole in this area of space, nor are there any Federation colonies.

Species and Lifeforms

Borg Collective - A cybernetic pseudo-species made up of thousands of assimilated species, Borg space abuts the Gradin Belt; however, a turbulent phenomenon known as Chaotic Space acts as a sort of natural barrier mostly protecting the Belt from the Collective.
Devore Imperium - A xenophobic and authoritarian culture, the Devore Imperium lays claim to a large swath of the Gradin Belt. It protects its borders with a strong military presence and inspects all who wish to pass through their space, harboring a particular aversion for telepaths.
Hierarchy Central Command - The operating authority for the Hierarchy, Hierarchy Central Command is highly stratified militaristic interstellar power technologically on par with Starfleet. It lays claim to a region of the Gradin Belt that it protects strictly and from which it conducts espionage and occasional raids against other inhabitants of the Gradin Belt.
Hirogen - A largely nomadic species, the Hirogen are occasionally found hunting "prey" in the Gradin Belt. Following their encounters with the USS Voyager, a small alliance of Hirogen has begun to seek an end to their nomadic lifestyle, forming colonies, establishing a space station, and claiming a region of territory on the edge of the Gradin Belt as their own.
Malon Cooperative - An advanced and economically-motivated culture, the Malon inhabit a region of the Gradin Belt. While they frequently trade with other regional powers, they have thus far shown no interest in interacting with Starfleet on account of their interactions with the USS Voyager over a decade past.
Turei Alliance - Born originally to defeat the Vaadwaur and later maintained by a shared desire to use the Underspace for their own purposes, the Turei Alliance considers themselves at war with the Vaadwaur survivors, fearful that the return of the Vaadwaur will weaken their reach and cut off their economies. The Turei pushed for a mutual aggression pact and settled for a non-aggression pact with the Federation, outlining the Vaadwaur as a common threat.
Vaadwaur - The first species known to have mapped the Underspace, the Vaadwaur used it to control massive swaths of the Delta Quadrant in antiquity. Almost a thousand years ago, the Vaadwaur were defeated by the Turei Alliance. Believed extinct until 2376, the Vaadwaur have since begun to move quietly again, their motives not fully understood, although many in the Gradin Belt fear that they will eventually attempt to retake control of the Gradin Belt and their former territories.

The Gradin Belt in Play

Compared to other areas of interest in the Delta Quadrant, all of the powers in this space are roughly equal to (and in some cases superior to) the Federation in terms of technology. None of them are as large as the Federation, but since the Federation is very far away and only connected to this area of space once every three months, Starfleet ships in the area are protected by the promise of likely Federation intervention if they're attacked more than any real military power being deployed. In other words, the Federation flag would protect you, to a point, but you're very far from reinforcements if things do go south.
The Starfleet ships stationed in this area of the space have largely been tasked exploring diplomatic and trade opportunities within the region, as well as keeping the peace as far as the prime directive allows. It is in the Federation's interests to keep this area of space from turning into a firestorm to let it serve as a check against Borg expansion, as their space lies just beyond this area.
This is the area most frequently explored by non-Federation Alpha Quadrant species such as the Ferengi, who are also looking for trade opportunities.