The Protectors of the Garden of Kadesh are a group of religious zealots that hide in the Great Nebula (which they refer to as the "Garden") and prey upon passing ships. Their motherships are capable of generating a hyperspace inhibitor field, and their swift, deadly Swarmer strike craft can overwhelm almost any vessel trapped by this field. According to the Bentusi, even the Taiidan fear the nebula, and no ships entering there ever return.
"After analyzing the data we collected from the Khar-Toba's sister ship we've been able to determine what happened in the nebula. While the Khar-Toba was able to limp to Kharak, this ship instead must have tried to hide here. They soon resorted to preying on ships passing through the nebula. In time the nebula became off limits to all shipping. They developed hyperspace inhibitor technology to trap prey from far away without leaving the safety of the nebula. Eventually it became the center of their existence and ultimately, their religion." - Fleet Intelligence
The Kadesh have a sad history; they and the Kushan were both descended from the ancient Hiigarans, who were defeated in the First Time by the vicious Taiidan and sent into exile. One branch of the refugees (the Kadesh) settled in the Great Nebula; the other (the Kushan) made it to Kharak. The Kadesh lived in the Nebula for thirteen generations as scavengers and pirates. They eventually developed their own fanatical religion, that worshipped the Nebula itself.
Eventually the Kushan passed through the nebula on their way to reclaim their homeworld, and the Protectors of the Garden attempted to trap them as they had other vessels. When the Kushan refused to surrender their vessels and join the cult of the Garden, the Kadesh ruthlessly attacked, even when the Kushan explained that their two peoples were related. So great was the Protectors' fear of the Taiidan and so obsessed were they with their religion that they fought to the last, even against their own kin. The Kushan were forced to destroy all of the Kadeshi needle-ships in order to disable the hyperspace inhibitor fields that prevented them from leaving the Nebula. Despite much wishful fan-created fiction to the contrary, there is nothing to indicate that any of the Protectors survived the passage of the Kushan through the Cathedral of Kadesh. They were zealots that fought to the last to defend their holy place.
"This is the Garden of Kadesh. For thirteen generations we have protected it from the unclean. The Turanic Raiders who came before you refused to join and were punished for this trespass. Like theirs, your ship has already defiled this holy place. If you have come to join we welcome you and will spare your ship until all have disembarked. If you have come to consume the garden you will be removed at once."
— Kadeshi Ambassador
Kadeshi were originally Hiigarans, during the Exile. When the Hiigaran convoy came to the Great Nebula, at least one of the ships broke off and stayed in Nebula, thus founding the Kadeshi race. The Kadeshi developed in isolation and later began to prey on ships passing through the Nebula. The Kadeshi called the Nebula the "Garden" and it eventually became the centre of their religion. An important tenet of this religion is that any outsider ship coming into the Garden defiles it, and therefore, the intruding ship's crew has only two choices: to join the Kadeshi or be destroyed. So strong is their belief in their religion that they prefer to sacrifice themselves rather than allow anyone to leave their holy place. The Kadeshi built large needle-shaped motherships and developed hyperspace inhibitors to capture and prevent ships from leaving the nebula. They proved to be great warriors, and eventually even the Taiidan came to fear the Great Nebula. According to the Bentusi - no one returns.
The Kadeshi Mothership came into being sometime after the Exile after a small band of survivors from Hiigara fled to the safety of the Great Nebula to escape their merciless Taiidan enemies. These survivors eventually came to call themselves the Kadeshi and as they grew in strength took to raiding civilian vessels seeking passage through the nebula. The Kadeshi Mothership was eventually conceived as a vessel capable of raiding enemy vessels while also ensuring the safety of the Kadeshi, who sought to isolate themselves from those who resided beyond the nebula.
The Kadeshi Motherships are constructed within the sanctuary of the Great Nebula.
Added by SkywalkerPL
There was not a single Kadeshi Mothership in existence, but instead at least three such vessels were confirmed to have existed in the Nebula during the Homeworld War. Together, these Motherships acted as the guardians to the Garden of Kadesh, the holy land within the Nebula which the would gladly fight to the death to ensure its survival.
In 9510 GSY, the Kushan and its Mothership Fleet arrived in the Great Nebula while on its quest to reclaim its homeworld, Hiigara. When the Kushan began to harvest the Garden of Kadesh, the Kadeshi Mothership arrived and sent its Ambassador to greet the newcomers. The Kadeshi offered the Kushan an opportunity to join them within the sanctuary of the Nebula, but upon rejection the Kadeshi Mothership sent its vast armada of Swarmers and Fuel Pods to destroy the Kushan. In the battle that followed, the Kushan were overwhelmed and attempted to jump into hyperspace, but were halted in mid-jump by the Kadeshi Mothership's hyperspace inhibitors. Trapped within the Nebula, the Kushan fought off the raiders and attempted to disable the enemy Mothership, which fled into deep space before it could be intercepted, thus disabling the inhibitor field. The Kushan then attempted once again to flee the Great Nebula.
However, the hyperspace jump again failed as the Mothership Fleet found itself pulled out of hyperspace and surrounded by three Kadeshi Motherships within the Cathedral of Kadesh, all of whom trapped the fleet with their powerful inhibitor fields. After the Kushan again refused the opportunity to join them, the Kadeshi attacked in full force, and the trio of Motherships sent Kadeshi Multi-Beam Frigates to destroy the Mothership. The Kushan and Kadeshi again fought for their survival within the boundaries of the Garden while the Kadeshi Motherships oversaw the battle from afar.
The Kushan first encountered the Kadeshi when the Kushan fleet burst into the Nebula while on their way to find their Homeworld. Unlike the Raiders and many other intruders, the Kushan fleet managed not only to repel attacking Kadeshi fighters, but also begun to strike at the Kadeshi Mothership, eventually forcing it to retreat. As the Kushan fleet moved deeper into the Nebula, the Kadeshi deployed two more Motherships for support and they trapped the Kushan Mothership in an inhibitor field while their motherships surrounded the invaders. Again, the Kadeshi offered the Kushan another chance to join them.
"Again we offer you a chance to join us and live here in peace" — Kadeshi Ambassador
"We cannot stay - we're on a journey. But let there be peace between us, for we have something in common. The hyperdrive technology left to us by our ancestors is identical to yours. The Homeworld we seek may be yours as well." — Fleet Command
"You will fail. The evil that drove us here will find and destroy you. From you they will know about us and come here. This cannot come to pass." — Kadeshi Ambassador
In response, the Kadeshi sent most of their ships in massive waves and attacking from all directions with Kadeshi fighters supported by their powerful Multi-Beam Frigates. However, the Kushan fought back using their Multi-Gun Corvettes supported by Drone Frigates that proved to be a match against the fast, but lightly armored Swarmers. Eventually, the Kadeshi retreated to a wreckage of an ancient ship, possibly the very one that first brought them to the Nebula. The Kadeshi continued to fight desperately but were finally defeated by the Kushan.
With the conclusion of the battle, it is assumed that the Kadeshi were rendered extinct due to the Kushan infiltration.
Many fans believe that the Kadeshi didn't go extinct after the battle with the Kushan fleet. Main arguments are that the Nebula was too big for the Kadeshi to be able to send a message about the Kushans and gather all the ships at the time the Kushan Mothership was in the Garden, and that the Kushans managed to reach 300,000,000 people on Kharak, so it's rather unlikely that Kadeshi population was only on these 3 Motherships; it would have been even more if they offered everyone the chance to join them. However, there is no trace of Kadeshi existence after the Homeworld War. Also take note that the Kadeshi always remain in the garden and won't leave it and no one had dared to go back there.
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.