Age of Arcanum

Second Era of history
The Second War, ie, the Divergence, marks the end of this era

From a history tome in Whitestone in Episode 70

"It speaks of the Betrayer Gods and many of their creations and their followers that began to lay waste to civilization and began to enslave the creators of those that remained on the side of light."
This seems to imply that these Betrayer gods instigated The Second War during the Age of Arcanum