So, here's a shortened version of my problem: Have played all the other races to some extent, want to play an Imperial in Skyrim, but don't know much about them due to lack of lore. The pocket guides are pretty good so far, and the imperial library has some okay information - but they seem to be light on the imperial lore.

For example, how did the Cyro-Nordic tribes come into contact? Were the humans in Cyrodil Nords, and then just started to call themselves Imperial, or are they in actuality two separate races? If so, where and how did the blood line get split?

Just a little confused is all. Seems like there isn't enough information on early Imperials, which is why I'm confused. Most of them just seem like Nords according to the lore.

They aren't Nordic, that's out dated scholarship from Tiber's reign. In Cyrodiils descend from Nedic tribes native to Cyrodiil.

Nords and Imperias are two seperate races entirely that split off from the same race, I don't know the name name i gues its Cyro-nords? That came from the continent of Atmora which is North of Tamriel.

Then I'm super confused. Because it says in the lore that the Nordic people started coming south to Cyrodil. So there were Nedes in Cyrodil before the Nordic invasion?

It also says here: http://www.imperial-library.info/content/pocket-guide-empire-third-edition-seat-sundered-kings-cyrodiil, that the Nords that fled from Skyrim were brought into slavery and eventually "became" the native people of Cyrodil.

So I'm not sure what to think.

The info is in-universe false. Whilst some/most Cyrodiils might have some Nordic in them, they for the most part they descend from tribes native to Cyrodiil long before the Nords returned.

Tamriel and Atmora were connected to each other in the beginning and then separated; Atmora to the north with the Nords and Tamriel with the humans that stayed.

So there were Nords in Skyrim, and there were Imperials in Cyrodil, and at one point the two merged to create the Cyro-Nords. If the Imperials didn't come from the Nords, then why have such a big emphasis on Cyro-Nords in the lore? So confusing...

Kinda, but mostly due to natural cultural mixing. But really, Cryo-Nord is an wrong term to use to describe them. People use in in-lore, but it's really just the Imperials trying to say that they are related to the badasses who founded the Fist Empire of Man. Even though they're not.

Edit: It's also trying to get the Nords to like them more, and to bring a sense of unity. I made this quote up, but it's like this: "The ancestors of us all suffered in the brutal attack of the Falmer on the Night of Tears! The elves are the enemy! For Cyrodiil and the Fatherland!"

It's not clear how things were in the very beginning, but at the opening of the First Era, there were tribes of men in Cyrodiil (especially in Niben), who were enslaved by the Ayleids. These are the ancestors of the Imperials. At the same time, there were giants in Atmora, a land to the north of Tamriel. These giants were the ancestors of the Nords. Over the years, they have steadily grown shorter as they lost their connection to the gods (so have the elves). During the First Era, the Nords came to Tamriel, landing in Skyrim. The leader of this exodus was named Ysgramor. At the same time, in Niben, Alessia led a rebellion against the Ayleids, founding the First Empire of Men.

The two cultures have had exchanged and intermarried, but that's not the reason for the misconception about the Imperials being descended from the Nords. Tiber Septim was born in High Rock, but when he became a god he created a new history in which he came from Atmora. As a part of this history, the idea of "Cyro-Nords" was also invented. This isn't to say these were lies - in Tamriel, powerful enough people can actually create new histories.

The ancient people of Cyrodiil were called "nedes," not "Imperials." Most ancient Cyrodiil stories are about the rebellion against the Ayleids, led by Alessia (a nedic slave), Morihaus (a winged bull), and Pelinal (a robot from the future). There's also the Remanada, which is about Reman, who founded the Second Empire.

It should be noted that Wulfharth, who posed as (and later, due to mythic reasons became) Tiber Septim was known as "Wulfharth of Atmora", suggesting that Talos is indeed from Atmora to an extent.