How do you form Greece?

[Kudera]

i have always seen people saying i formed greece as the knights and ragusa but how do you do it i dont see a national decion

[Sir Slasher]

normly released in peace or from rebels

[Kagemin]

Potential Requirements

Country is not:
Holy Roman Empire
The Papal State
Ottomans
Byzantium
Byzantium and Greece do not exist
Country is not a colonial nation
Primary culture is Greek
If country is AI controlled, it must have at least 3 cities
If country used to be a colonial nation, it must be player controlled

Allow

Administrative Technology at least 10
Is a Monarchy
Is not a subject nation
Is not at war
Owns and has cores on:
Epirus
Morea
Athens
Naxos
Achaea

Taken from this page: http://www.eu4wiki.com/Greece
Also has a general strategy on how to do it under 1.7.