What are the prerequisites to form an empire?

[Fe1000]

After picking random nations in the start only to look at their decisions i noticed not all nations have the decision to become an empire. Other than the obvius 50 provinces, what are the prerequisites to form an empire? I guess it could be civ level in the capital, but that wouldn't make sence since Sparta can become an empire but Egypt can't. It's also not related to to gov type, since both Sparta and Macedonia are aristocratic monarchies but Macedonia can't become an empire. Is it tag related?

 

[Lofman]

It simply requires positive stability (and being some form of monarchy) for the decision to actually show up.

 

[Fe1000]

It simply requires positive stability (and being some form of monarchy) for the decision to actually show up.

Thanks. Does it also require to not exist another empire on the map or it's just a rumor I heard?

 

[DKM]

Thanks. Does it also require to not exist another empire on the map or it's just a rumor I heard?

Just a rumor.

 

[rpstrategist]

You also need 50 provinces. (and being a monarchy with positive stability as mentioned above)

 

[Olaus Petrus]

You also need 50 provinces. (and being a monarchy with positive stability as mentioned above)

This is correct. I just want to add that if you're playing as republic, then you have to switch to dictatorship (which is one form of monarchy in the game), before you can take the create empire decision.