At this year's Hellfire Gala, the X-Men received a devastating defeat when the forces of Orchis launched a deadly attack on the mutant celebration, and after killing a number of X-Men (including Jean Grey, one of the most powerful members of the X-Men), Professor Charles Xavier was blackmailed into sending all of the mutants off world through the Krakoan teleportation system. At the end of the issue, Xavier can't find any of their minds, so he believes he was tricked into killing hundreds of thousands of mutants, but in reality, they were just strewn throughout the Marvel Universe.
Source：https://www.cbr.com/marvel-first-look-at-realm-of-x/
