We have updated our Community Code of Conduct. Please read through the new rules for the forum that are an integral part of Paradox Interactive’s User Agreement.
You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
I think you can form the kingdom of Westeros if A) the Iron Throne doesn't exist and B) you personally (not as vassals) hold 4 (I think) kingdom/empire titles in Westeros.