- Sorin being was born about 6000 years ago according to a lost thread from the Gleemax forums (See here: http://www.mtgsalvation.com/forums/magic-fundamentals/magic-storyline/515633-birth-of-sorin-markov). I believe the date is also given in some Doug Beyer Tumblr posts. Sorin being 18 when vampirism happens I've taken from the MTGSalvation Timeline. Presumably this can be traced back to the lost forum post.
- The Eldrazi were imprisoned about 6000 years ago, also according to Dough Beyer (http://dougbeyermtg.tumblr.com/post/95003484139/random-question-for-timeline-purposes-how-long-were). Hence I've put it "A relatively short time" after Sorin ascends.
- Sorin being centuries old by the time he creates Avacyn comes from the article Sorin's Homecoming (http://archive.wizards.com/Magic/magazine/article.aspx?x=mtg/daily/stf/177)
As always, the dates relative to surrounding dates are speculative. There could well be overlap with the Dakkon/Fallen Angel/Sol'kanar stories, but I've opted to keep all related dates together so long as no clear dates are given that sepparate the events.