What Genosha is
Chris Claremont and Marc Silvestri introduced Genosha in Uncanny X-Men #235 (October 1988) as an apartheid-era island nation with mutant enslavement. The framing was a deliberate X-Men allegory for South African apartheid; the nation became a recurring X-Men setting throughout Claremont’s late run and beyond.
The 1999 ‘Magneto’s Genosha’ arc reframed the island as a mutant homeland under Magneto’s sovereignty after the human population’s collapse. Grant Morrison’s 2001 New X-Men #115 destroyed the nation in Cassandra Nova’s mega-Sentinel attack, killing approximately sixteen million mutants in a single issue. The destruction is one of the most consequential events in modern X-Men continuity.
Collector context
Uncanny X-Men #235 trades in the four-figure range at CGC 9.6 and above. New X-Men #115 (the destruction issue) trades in similar ranges and is recognized as a Modern Age X-Men key.