Help with the Kingdom (Mount Blade 2: Bannerlord)

In short, fucking, I started to go through the type for helping the empire and I gave the banner, then I decided to leave and create my own kingdom, I left and I have a 4.5 clan rank there is a city of Hubya (I don’t remember the name) and 143 war, but I do not have a button Kingdom,
Can you tell me that I need to look for old preserves until the times when I gave up the banner or can I somehow make the kingdom in a different way?