The Startide Nexus is a recently created vortex in space that acts as a stable dimensional pathway between the Sept Worlds of the T'au Empire and the Nem'yar Atoll, which is located within the Imperium.[1b]
The nexus was was initially created when the fleet of the T'au Empire's Fourth Sphere of Expansion ignited their AL-38 Slipstream Module jump drives in an attempt to travel beyond the burning Damocles Gulf. However, the fleet's were AL-38 Slipstream prototypes, which had been tested only on single vessels, and when the numerous jump drives were activated all at once, they created a tear into the Warp which engulfed the fleet. Though the T'au Empire assumed they had been destroyed and mourned their passing[1a], the Fourth Sphere had survived, but were trapped within the Warp and preyed upon by Daemons. It was only after the Great Rift was formed that the remnants of the Fourth Sphere of Expansion's fleet was freed, when a powerful sentience pulled them from the Warp. It was this emergence into realspace that caused the Startide Nexus to fully materialize.[1b]
Though they did not know where they were, the Fourth Sphere's Commander, Surestrike, led them to colonize several nearby worlds, as well as fortify their end of the Startide Nexus[1b]. A drone was then sent through the Startide Nexus and ten years after the Fourth Sphere's initial disappearance, the drone was found by the T'au Empire. This quickly led to the discovery of the Startide Nexus[1a] and the Empire began fortify their end of the vortex. However, it was only after a recon probe returned with solid proof of the Fourth Sphere's survival that the Ethereal High Council allowed the T'au Empire to launch an expedition into the Startide Nexus. This Fifth Sphere of Expansion was led by Commander Shadowsun, and when it emerged from the Startide Nexus the survivors of the Fourth Sphere were there to greet them and were integrated into Shadowsun's command. She then led her forces into expanding the size of the Nem'yar Atoll, which led to the creation of several new Sept Worlds, including many Imperium worlds[1b]. This expansion was brought to a halt several months later, however, when a massive Death Guard armada appeared within the Nem'yar Atoll and began moving towards the Startide Nexus. Though caught by surprise, Shadowsun quickly rallied her forces against the Chaos invaders and was engaged in a desperate battle to prevent the Death Guard from reaching the Startide Nexus and gaining a pathway to the heartlands of the T'au Empire.[1c]
On the side of the Nexus linking to the greater Tau Empire, the region of space around the anomaly has been fortified to such an extent that it rivals the Tau's capital of T'au itself. On the other side of the rift, the entrance is heavily protected by the worlds of the Nem'yar Atoll.
- 1: Codex: T'au Empire (8th Edition)