[quote=@yoshua171]
<Snipped quote by Zarkun>
Is it known [i]why[/i] it happened? Aka, what caused Zeref and the "Slayers," to do what they did? Or is it just documented that they did "X thing" thus bringing the world to a time of darkness before they were defeated.
[/quote]

There are no concrete reasons available to the OOC public or the IC public at this time. Plenty of theories but nothing concrete. We GMs have...picked a couple of reasons that will all be revealed as the plot reached that point.