Timeline of the settlement and early construction of Nexus Prime.
Second version of early timeline from Rod Halfking:
Mica, Aragorn, and Bif go to Earth in the 1980's. Dr. Wiley writes important physics papers, Bif becomes a celebrity wrestler.
Dragon Mountain - dragon escapes
Spidermoon (The Needle) - the Nak must flow!
Destabilization of Harn through excessive technology.
Collapse of Krynn, lost dragon war. Takhisis' ascendancy after Mica created a power vacuum by banishing Chemosh with a sphere of Annihilation. Chemosh can't return to Krynn for a hundred years, the undead armies all die. Takhisis intervenes on the part of at least one Death Knight (possibly Lord Soth?), making it human again.
The Irda Tree, at that point the last standing tree of its forest, is rescued. Seth turns it into a red haired half-elven lady who returns with the party to Nexus Prime.
Raistlan blows up the Superbalas. It is raised again and used for the evacuation of Dragons and other Good survivors of Krynn to Arda.