So according to the patch notes:
This is the secret area they mention:
I would like to propose a theory, but a very simple one. if anyone has anything else they think may be possible, please post here!
It seems that the cave painting has two “teams”.
The left has 2 warriors, one archer, one rogue, and one “tank”.
The right has 2 archers, one “tank” and what looks to be either an archer moving or perhaps a mage.
The left has a “wyvern” type dragon. However the upper body is a bit light for that type.
The “wyvern” is clearly fire based.
The right has a “ampithere” type dragon.
We don’t know what element or type it is because it is not attacking.
It looks more like it is dodging.
My proposal is that this could possibly be something that would be implemented when multiplayer comes out. I assume that the developers have already planned a roadmap for this.
It could be either faction based or choice based as well. This could also be something like a first add-on/DLC that they add. Judging by the lack of mages in the picture, this could even be a time BEFORE the divine era but AFTER the ancient era. Considering there is an obvious large gap between the two. I could probably theorize for a long time but I want everyone else to see what they think.