Short answers, pulled from the story.
Stan Lee and Jack Kirby launched The X-Men #1 on the 2nd of July 1963. Marvel publisher Martin Goodman rejected the initial title The Mutants because he believed readers would not understand the word.
Writer Len Wein and artist Dave Cockrum introduced a completely new team with Giant-Size X-Men #1 in May 1975. This roster included Colossus from Russia, Nightcrawler from Germany, Storm from Kenya, Thunderbird from Apache descent, Banshee from Ireland, Sunfire from Japan, and Wolverine from Canada.
Magneto is a Holocaust survivor who explicitly referenced Nazi concentration camps by uttering never again during a 1992 animated episode. The fictional island nation Genosha served as an apartheid allegory where mutants were segregated and enslaved with numbers burned into foreheads.
Retailers pre-ordered over 8.1 million copies of X-Men #1 from October 1991 generating nearly $7 million though actual sales reached closer to 3 million copies. Guinness World Records lists this issue as the highest selling comic book issue in history.
Jonathan Hickman announced a complete relaunch of all X-Men titles on the 14th of May 2019 during San Diego Comic-Con. Two rotating bi-weekly six-issue limited series called House of X and Powers of X began the new era establishing Krakoa as a sovereign nation for mutants.