How would you set up civs in a big mod?

[CaptainLost]

If you had a mod based on diversity, with each civilization having unique everything, how would you set up the civilizations?
Would it be:
1. Each civ has a specific "strong" time period, which reflects the period the civilization actually existed in. This would be the only time the civ has anything unique, and for the rest of the game the civ would be just like any other civ. For example, the American civilization would have all of its unique elements starting around 1776, or maybe even before then as "American" colonists.
2. Each civ has one certain time period, reflecting the period the civilization actually existed in, which is the only period that civ can play in. You would not see Americans before the 1700s with this one.
3.Each civilization has its roots, and its branches, traced out in one "line', which extends from the beginning of the game to the end of the game. For example, Ethiopia would start out as African tribesmen, then become the kingdom of Axum, then finally become the kingdom of Ethiopia. The Roman empire would fall into either Byzantium or the Western Roman Empire, whichever one you picked. (So you wouldn't actually choose to play Rome, you'd choose to play Byzantium or Western Roman Empire, and play as Rome during some time in both.)
4. Each civilization has "what-if" hypothetical unique elements for any period that the real civilization didn't actually exist. In this version the Celtics would have unique Celtic tanks in the late game, Americans would have unique American spearmen early on, and so on.

Post your thoughts below!

 

[PixelStrategist]

To keep civ interesting I would have option four (it makes the game less linear)

 

[Flying Pig]

The downside of that is that if you start off playing as the Romans and conquer Europe, there'll never be an England, France, Germany, Spain, America, HRE or anything like that for the rest of the game. I quite like RFC's solution, which is to have new civilisations spawn within old ones that occupy their territory. This also gives the option of taking control of one of those new civilisations, so you could start as the Romans, have the English as your 'successor state', then play as America.