It is the end times m8. Archaon is a playable character in the game as well as Grimgor. Sooo I'm not sure what you mean but it's around that time period, so technically it is the End Times. If you mean it's not "historical", that would be a dumb excuse because it's a total war game. Non canon shit here yo.
The forces of Chaos wipe out the living world. Literally kill everything. GG no RE.
(I'm talking about the Canon lore being shit. The game itself is good, just the lore is shit)
Here's the Lore that i find very distasteful:
Dark Elves leader Malekith was pretty much a nice guy and all that raping, plundering etc DE's did is absolved and Malekith becomes Phoneix King(There is lots of other stuff that happens that bascially ruins DE lore. Mainly their "Slaneesh cults" were never Slaneesh, etc. etc. they was just misunderstood)
Mannfred von Carstien is useless in lore and betrays every faction at least once and then blows world up by killing Balthazar Gelt.
Dwarves get Reckt. Chaos dwarves are "non existant" before the world ends(being wiped out by greenskins).
Lizardman basically have skaven fuck them up. Skaven blow up Morsliebb(the moon), Wiping out Lustria and Lizardman flee in spaceships.
Orcs fight huge army of chaos. Archeon gets reckt by Grimgor. And instead of killing Archeon, Grimgor Turns his back on the downed Archeon and gloats, then Archeon Chops his head off.
Bretonnia's "lady of the lake" is nothing more than Lileath(Elven Goddess) who reveals the most SHITTY part of the lore:
The current "gods" are nothing more than the survivors of the world BEFORE this one who just recreated it as they saw fit. A continuation of the death/rebirth cycle.
Once Chaos knocks off everyone to death, the world(now called Mallus) get thrown through the cosmos with Sigmar(who takes over Franz after he "dies") holding on until some dragon(who was somehow not killed when "chaos wiped out all life in galaxy") grabbed the world. Sigmar then recreates the world with most of the previous races somewhat still around(Elves, humans, undead/vamp & greenskins are all that are mentioned). Following this all gods join up for a time and prevent chaos from rejoining. Chaos breaches, imprisons all the other worlds save Sigmars. Sigmar create Storm Elementals (AKA Fantasy Space Marines) and starts fighting Chaos (AkA Fantasy Warhammer 40k) and then you get "Age of Sigmar" game.
The end.