Over the course of the trilogy, the galactic community come to learn that the Protheans were mostly wiped out over 50,000 years prior by the Reapers, sentient starships that normally occupy the void between the Milky Way and the Andromeda Galaxy, but appear every 50,000 years with the sole purpose of wiping out emergent organic species as well as any evidence of their own existence. Unlike their predecessors in previous cycles, the Protheans had learned of the Reapers and prepared for their arrival, though they were unable to prevent their own extermination by the Reapers. Their preparations survive into the next cycle, in the form of the Crucible. The "Mass Effect" series starts as the nascent appearances of the Reapers in this cycle have occurred, beginning with the indoctrination of a rogue turian Spectre, an influential asari Matriarch, and a "heretic" faction of geth who broke away from the Geth Consensus to further their plans of return.