Maybe some of you ES Historians can help out here i was reading some of the nordic lore and its says that Tiber Septim was called Ysmir The dragon of the north But it also says that King Wulfharth is known as Ysmir the dragon of the north. I thought ysmir was an alias but could it be a Title to Great Nordic men?

Ysmir = nordic name of Talos.

Also, Tiber had Wulfhart act as his doppelganger in the battlefield, while Tiber was doing Tiber thing, to give the impression of he's everywhere, or something like that.

but then why do they call wulfharth ysmir?

made a quick edit. Also, Talos is the combined oversoul of Tiber, Wulfhart, and Arctus.

And then because a lot of people believed he was in multiple places at once, history retconned itself to make that true.