According to records accessed by James Holden on Ring Station, the galaxy-spanning alien civilization responsible for the creation of the protomolecule, Rings and the Slow Zone was destroyed by an unknown agency. This mysterious force demonstrated the ability to neutralize the civilization's hive-mind or collective consciousness, and as its influence spread throughout the galaxy the civilization was forced to resort to extreme measures, destroying entire solar systems in a bid to stem the "infection".On Ilus, Dr. Elvi Okoye and the Investigator were the first to encounter an artifact left behind by the force that destroyed the alien civilization. The object, appearing as a dark, floating sphere bordered with bright light, was undetectable and invisible to the Investigator and other alien machines, but would render them inert if any passed within its radius. Elvi passed through the object herself while attempting to use it to shut down Ilus' defenses, but she survived the experience without ill effects. She did experience a feeling of perceiving the very smallest of things, down to her component atoms. While passing through the Laconia ring gate, the crew of the Barkeith, a Donnager-class Battleship belonging to the breakaway MCRN fleet, experienced a similar phenomenon as Elvi had inside the Ilus artifact. The ship and all hands aboard were lost during transit. The remnants of the Free Navy are destroyed by the same phenomenon as experienced by the Barkeith. When the Laconian Empire's Magnetar-class battle cruiser Heart of the Tempest fired its magnetic beam weaponry, the entire Sol system experienced a simultaneous blackout that didn't account for light delay. After everyone woke up, the crew of the Tempest found a sphere indentical to the one from Ilus aboard their ship.

Winston Duarte instructs the Laconian Science Directorate to carry out an experiment to determine if the disappearance of ships traveling through the ring gates are the result of a natural phenomenon or the conscious work of a hostile intelligence. To test this, an unmanned ship would be sent through a gate, followed immediately by a second unmanned ship carrying an antimatter warhead. This was predicted to trigger a "dutchman" event, in which the second ship would disappear, and subsequently detonate its warhead upon arriving wherever the vanished ships had been ending up. The experiment was carried out in the Tecoma system, which was judged to be a safe testing ground owing to its lack of habitable planets.

The experiment resulted in the hostile aliens triggering the collapse of the Tecoma system's neutron star, causing a gamma-ray burst aimed directly at the Tecoma gate. The aliens then proceeded to invade the Slow Zone and cause the disappearance of all human constructions within, including Medina Station. Only the crew of the Falcon, including Elvi Okoye and Fayez Okoye-Sarkis, survive this encounter with the Unknown Aggressors, which are soon labeled as "Dark Gods" by the Laconian military establishment.

After the first Laconian antimatter experiments and the attack on the Slow Zone, the Unknown Aggressors continue their consciousness-breaking attacks on humanity, with the episodes coming more frequently, without warning, and differing in their effects. Dr. Okoye speculates that the hostility of the Unknown Aggressors is related to travel through the rings, which hurts them somehow, and suggests that the actions of Laconia have resulted in the aliens now viewing humanity as a threat. She likens the episodes of lost consciousness to how humans might treat an illness, speculating that the different nature of subsequent episodes is akin to switching from penicillin to tetracycline.

Artifacts and Technology Edit

While little is known about the alien civilization that created the protomolecule, even less is known about the entity or entities responsible for its destruction. As of yet, only two objects have been encountered that appear to have been created by the unknown agency: the mysterious sphere on Ilus, which could destroy networks like the Ilus defense system on contact, and the sphere on the Tempest.

The object's effects on a human observer are highly unusual; while inside the object on Ilus, Elvi described herself as being able to perceive increasingly small objects and phenomena, eventually becoming aware of the individual molecules and atoms that composed her body.