Overview
BR-000, also called the Primary Black Ring, was the first ever known Black Ring and the largest known Black Ring to date. It is believed to have erupted as a result of the DisSea Explosion in N.F. 084, but in truth the Ring actually existed long before then. BR-000 was born from the wreckage of the Perishing Star, and was the epicenter from which apocalyptic calamities swept the rest of the globe, ultimately wiping away the old world order and ushering in the Nightfall era. The Keylan Expedition sought to explore the "Death Zone" surrounding the meteorite; this undertaking ultimately marked the foundation of DisCity. Thus, for the Black Ring's existence to have been forgotten in the time between the early Nightfall era and the DisSea explosion is likely the result of strict information control by Paradeisos. It is likely that the original contamination zone explored by Keylan was covered with water over time as the impact crater became the DisSea, but that BR-000 continued to exist and was simply not discovered until it expanded during the DisSea Explosion decades later. The original Death Zone may have also covered a much greater area than the modern DisSea, as Maria (the site of present-day DisCty) was deep within the contaminated area. In this case, BR-000 would have been greatly reduced by cleanup efforts after the establishment of the EDGE Accords.
BR-000 is the epicenter of many phenomena above and beyond what are normally observed in other Black Rings. The Phantom Moon appears frequently inside the Ring; Apostles constantly move towards the Ring, with some species that are only known to exist inside of it; normal discrepancies in the passage of time escalate into temporal storms that distort the experience of time by up to tens of thousands of years. These occurrences are likely related to BR-000's direct connection to the Deep Mania.
Expansion and Containment
The DisSea Explosion transformed the DisSea into an inhospitable center of corrupted spiritual essence. The event resulted in 87,231 confirmed deaths and over 200,000 Maniacs, and the Ring's contamination field spread rapidly before it was ultimately contained by the newly-formed FAC. The FAC constructed the Broken Frontline, which separates it from the rest of the city and keeps the monsters and corruption within at bay.
Although contained, BR-000 remains volatile. The Ring has regular waxing and waning periods of activity, corresponding to the rise and fall of the Illusory Moon. In addition to these somewhat-predictable changes, BR-000 also frequently responds to and resonates with Mania-related crises throughout the city. In N.F. 104, the appearance of BR-002 in the Inner Bay caused rapid expansion of BR-000 due to their close proximity. It was barely halted at the FAC's third Broken Frontline. BR-000's core body is strictly controlled by the FAC, but its radiation is expansive and stretches well into the Inner Bay. During active periods, the Ring's influence has uncontrollable effects on Sinners throughout the City and possibly even beyond.