I reformed the Empire of Cyrodiil! Because my character is a proud-ass git, I've decided that for roleplaying purposes (since the game doesn't keep track at all) that the year that I reformed the Empire of Cyrodiil is the beginning of the Third Era (Tiber Septim didn't do it until he actually got control of all Tamriel IIRC; at least, the plot of Redguard revolves quite a lot around Tiber Septim trying to get Hammerfell into his Empire of Tamriel in the late Second Era IIRC). The Empire of Cyrodiil was founded thus:
2E 450: Carmalo began his conquest of Cyrodiil.
2E 524: Carmalo founded the Kingdom of Cyrodiil. In the meantime, he became immortal through magic.
2E 533: Carmalo began conquering Skyrim. This time, he was a bit more efficient, trying to grab claims and such as quickly as possible.
2E 583: Carmalo had conquered most of Skyrim by this point. In the meantime, he had also gained the Amulet of Kings.
3E 1: Carmalo created the Empire of Cyrodiil, as joint king of Skyrim and Cyrodiil, then promptly gave control of Skyrim to Neran, his great-great-grandson.
3E 11: Carmalo began conquering High Rock.
3E 26: Carmalo founds the kingdom of High Rock. High Rock, compared to Skyrim, was hilariously splintered (rare was a realm more than two counties, and those tended to be duchies that didn't hold much of their de jure area, allowing for usurping to destabilize things a lot) and half the size besides and gives control of it to Donvar, his great-great-great grandson and Neran's son.
3E 29: Neran dies and is replaced with Skyrim's tanist and Neran's grandson, Cocisto. His son is a Breton, ain't that something.
Carmalo is 189 right now. It's actually quite lore friendly that people aren't suspicious; the
Janus Hassildor at the time of Oblivion had been around for over a hundred years IIRC and people were just like "oh he's a powerful mage" (though, really, he's a vampire; the fact that he was well-regarded probably helped convince people that nothign was too amiss).
Also, the oldest living mortal right now is Alfe Fyr, Divayth Fyr's first daughter/wife/clone. Divayth Fyr appears to have been assassinated 2E 542. There should probably be some checks on learning for avoiding assassinations for mages, if that's possible. It probably isn't, now that I think of it, since there aren't already. Bolyn Hlaalu currently controls Tel Fyr, weirdly enough.