This is my opinion on the mythos of diablo. Nothing in Diablo 2 ever happened. That game completely lacks the atmosphere of the original (though some of the short movies still have some). I guess you could say that my stance on Diablo 2 is similar to the one Star Wars fans have toward the phantom menece.
For a little bit of insight play through the quests in singleplayer and talk to the townsfolk a lot. Some of the things they say might give some insight into what the world outside of tristram is like. The magic rock quest comes to mind, in it Griswold talks about the trade caravans some and the 'dark riders' that have been around the countryside since the evils began. It's been awhile since i played through singleplayer though.
Addition: Also read the diablo manual.
For a little bit of insight play through the quests in singleplayer and talk to the townsfolk a lot. Some of the things they say might give some insight into what the world outside of tristram is like. The magic rock quest comes to mind, in it Griswold talks about the trade caravans some and the 'dark riders' that have been around the countryside since the evils began. It's been awhile since i played through singleplayer though.
Addition: Also read the diablo manual.
Y'know, there are a million fine looking women in the world, dude, but they don't all bring you lasagnia at work. Most of them just cheat on you.