I've had this banging around for a while now, so I've added Ashake into the mix and stuck it up.
c 38 000 BCE: An alien spacecraft crashes in the Arctic, and lures an exiled tribesman to millennia of torture.
c 3000 BCE: Storm's ancient ancestor Ashake meets Illyana Rasputin and Danielle Moonstar after an attempt to flee the Shadow King results in Illyana teleporting them both to ancient Egypt.
1875: A motoring accident in the Transylvanian Alps leads Diablo to create Gilded Lily from the body of one of the victims. He then tutors here in the art of alchemy before being seemingly killed by an angry mob in the classic mould.
1935: Charles Xavier is born to Brian and Sharon Xavier, workers on an American nuclear project never revealed to the general public.
1942: Iceman arrives at the end of a jaunt through time and is involved in a battle that accidentally claims the life of his father years before Bobby was destined to be born, resulting in a temporal paradox ultimately resolved by the avatar of oblivion.
1945: The Trinity nuclear test at Alamogordo on the 16th of July kills Brian Xavier.
1946: Sharon marries Kurt Marko - also at Alamogordo, and blamed by Charles for his father's death - who then moves into the Xavier family home.
c1948: Kurt is killed in a lab accident. Soon after, Xavier discovers his psychic powers.
1953: After joining the army, Xavier (along with Kurt's son Cain) is deployed to Korea.
1957: Ororo Munroe is born.
1958: Jean Grey is born.
1960: The group of mutants assembled to commit evil by staggeringly racist villain The Claw are freed from their captor's bondage. They agree to enter into suspended animation, coming out once every ten years for a week to determine whether mutants have finally overthrown humanity, and if so, to offer their entirely uninformed opinions as to how to rebuild the planet.
1961: Bobby Drake and Kurt Wagner are born.
1962: Xavier meets both Erik Lensherr and Gabrielle Haller, the latter of whom will one day bear him a son.
1964: A crewman is washed from the deck of the trawler Mary D and finds a golden egg on the sea-bed; this rapidly hatches into a hominid girl her finder names Marinna. Piotr Rasputin is born.
1966: Rogue is born.
1968: Xavier faces Lucifer in Tibet, in a struggle that costs him the use of his legs. Dr Michael Twoyoungmen loses his grandfather and his pregnant wife; the latter of which his young daughter blames on him. Richard Easton finds a ceremonial headband at an archaeological dig in the Arctic, and as a result is requested to and agrees to impregnate Nelvanna, Goddess of the Northern Lights.
1969: Ororo Munroe gives up her life as a street-thief in order to follow a strange compulsion drawing her to the Serengeti. Katherine "Kitty" Pryde is born.
1972: James MacDonald Hudson learns his mechanical suit design is to be used by the US Army in Vietnam; he responds by destroying the blueprints. His boss, Jerry Jaxon, is fired as a result, and swears revenge.
1974 James Hudson and Heather MacNeil are married.
1977: Xavier founds the X-Men. Richard Easton returns to the world after impregnating Nelvanna, and quickly goes insane.
1978: Doctor Michael Twoyoungman becomes a shaman (named Shaman, obviously) under the tutelage of his grandfather's ghost. He then aids Nelvanna in giving birth to Snowbird, and fosters the baby.
1979: The true identity of the Hulk is revealed to the world. Walter Langkowski was at college with Bruce Banner, and so is inspired to try his own hand at gamma ray experimentation.
1980: James Hudson dons his Weapon Alpha (later Vindicator, still later Guardian) costume for the first time, only to learn that his closest friend and collegue Wolverine has quit Department H in order to join up with an American professor for reasons unknown.
1982: Walter Langkowski triggers the gamma ray bombardment process that mutates him into Sasquatch. Puck and Marrina meet in Beta Flight.
1983: The creature in Lake Ontario claims its first victim.