The Great Nebula of Kadesh, also known as the Gar'de'n' 'of Kadesh, is an area of the galaxy, which is either one gigantic nebula or a dense region of nebulae, that disrupt all sensors and communications. Either way, it is the largest such astronomical feature in the entire galaxy, spanning several thousand light years in length (coreward to rimward), and nearly 10,000 light years in width (arc) according to most galactic maps. Many theories abound as to how it formed, but none are proven.

The resource value of the matter (gas and dust) inside the nebula is incredibly rich, leading many a traveler and explorer to wander inside its boundaries in hopes of harvesting their way to fortune. Many entered, but none returned due to the attacks of a race known as the Kadeshi, relatives of the Kushan. They roam freely inside the reaches of the Great Nebula, never leave its protection, and protect the nebula as a sacred and holy garden. They believe that any outsider venturing into the nebula defiles it. This lifestyle is made easier by the fact that the Nebula's energy levels are so high that even the Mothership's sensors had difficulty to compensate, letting the Kadeshi ambush them when they passed through.

Some speculate that one reason the Taiidan never acted sooner against the Kushan people was simply that they never knew where they ended up after The Exile. The Great Nebula may have blocked all forms of astronomical 

observation. As such, and due to the danger of the Kadeshi, the space in and around The Great Nebula remained unexplored and officially quarantined by the Galactic Council.

As a background image for the missions inside the Great Nebula the images of M8 (Lagoon Nebula) were taken.