Large Magellanic Cloud

The Large Magellanic Cloud (also called the Greater Magellanic Cloud) and known as Path Kethona by the Forerunners is one of the two Magellanic Clouds, located 160,000 light years from the Milky Way.

History
A local dwarf galaxy orbiting the Milky Way, Path Kethona was once the site of Precursor activity. One local system was home to a network of star roads unlike anything seen in the parent galaxy. After the Forerunners rebelled against the Precursors, around ten million years BCE, and began a genocidal campaign to root out their creators, the Precursors eventually retreated to Path Kethona. However, the Forerunners followed with an enormous fleet of warships, constructing a series of probability mirrors to reconcile the massive causal breaches caused by the transit. All but a few Precursors were exterminated; a small number survived by entering suspended animation or reducing themselves to molecular powder programmed to reconstitute their forms at a later time. Ships bearing the powder were sent on their way toward the Milky Way, some eventually crashing on worlds in the galactic margins. Millions of years later, the Precursor molecules—corrupted over the eons—would spawn a virulent parasitic lifeform: the Flood.

During the war, some Forerunners serving aboard the fleets sent to Path Kethona began to object to the complete genocide of the Precursors as a crime against the Mantle. Many of these dissidents were summarily executed, while some were exiled on a barren world within a nebular region known as the Spider. An artificial ecosystem was constructed entirely from Forerunner genetics to sustain the Forerunners on the planet, who would come to adopt a primitive lifestyle and undergo divergent evolution from the mainline Forerunners, resulting in several physiological differences between them. Ironically, the marooned Forerunners would outlive their former compatriots who finished the genocide, the latter never returning to the ecumene out of immense guilt over their actions.

Meanwhile, the truth about the passing of the Precursors faded into legend and was eventually forgotten over the eons. According to the ancient myths of the latter-day Forerunner civilization, prehistoric Forerunners had conducted a great scientific expedition to Path Kethona more than ten million years earlier, a distorted version of the final phase of the genocide of the Precursors. In addition, prevailing theories held that the satellite galaxy was the point of origin of the Flood. Several millennia after the Flood's first emergence, around 98,395 BCE, the Librarian organized and led an expedition to Path Kethona with the intent of examining the origins of the Flood as well as the veracity of the legendary Forerunner expedition. Aboard the ship Audacity, the Librarian and her crew of seven traveled to Path Kethona. Initial scans found the galaxy seemingly devoid of technological civilizations—or any life at all. In one system, however, the crew of Audacity discovered an impressive network of Precursor artifacts—as well as a fleet of ancient Forerunner warships and the probability mirrors used to reconcile their arrival millions of years earlier.

Further scans revealed a single planet orbiting an orange star with a possibility of supporting life. Traveling to the planet, the Librarian and her crew discovered the primitive Forerunners and the planet's peculiar ecosystem. The Librarian was taken by a local female to a moss-like growth which had adapted to record the locals' history. It was through this repository of knowledge that the Librarian learned the origin of the locals, as well as the true nature of the prehistoric Forerunner expedition to Path Kethona: while ancient Forerunners had indeed traveled to Path Kethona, the journey had not been for the purposes of exploration, but to eradicate the last of their creators. Deeply distraught, the Librarian and her crew subsequently returned to the galaxy; she did not reveal what she had learned to anyone, until her testimony to Catalog over 900 years later.

All life and Precursor architecture in Path Kethona was wiped out when Master Builder Faber fired Omega Halo's directed pulse toward the satellite galaxy during the Battle of the greater Ark in the last days of the Forerunner-Flood war in 97,445 BCE.

List of appearances

 * Halo: Silentium