A massive melange of plasma and hydrogen and helium gases, the Tarantula Nebula is the largest nebula known to humanity. It's super-luminosity means it is visible from planets thousands of light-years away and that it creates permanent daylight on the worlds which lay within its boundaries. A highly active star-forming region, the Tarantula Nebula is home to an unusually large number of systems, many of which have formed from the stellar gases which are in abundance. Many of these systems are home to former Imperial colonies which have seceded from the Imperium within the last decade, forming the nucleus of the Free States which claims the entire Tarantula Nebula.

Travel through the nebula is difficult; the gases interfere with the normal engine functions of starships, interrupting the Triborozon reaction which allows a starship to travel great distances in a short space of time. It is impossible to maintain a subspace tunnel for prolonged periods, meaning that starships wishing to travel to destinations within the nebula must make a series of short, calculated trips. Travel times between some of the farthest points in the nebula can take almost three weeks, making the nebula not only the most difficult region to traverse but also a popular one for those seeking interstellar cruises.

The nebula is loosely patrolled by forces of the Volunteer Fleet, now that the Imperial Fleet has withdrawn. This Volunteer Fleet, a rag-tag collection of hundreds of vessels which have pledged allegiance to the Free Worlds, attempts to maintain law and order in the region, chasing off pirates and raiders and attempting to aid stricken or distressed vessels. The difficulties of travel, however, make this task more complicated, and the lack of available vessels even more so. It is believed a number of illegal anchorages have sprung up to facilitate pirates and raiders and service a thriving black market economy. Rumours also abound of secret Imperial and Alliance outposts and listening posts to collect information on the Free States and use them for an eventual invasion and re-occupation of the region by whichever side is ultimately victorious in the civil war.