I just conquered Rivacheg. How to change player faction troop tree?

[Valiente]

How do I do it? For some reason my troops are Swadian and I want them to be Khergits! Lancers are awesome!

 

[Windyplains]

Speak to your faction's minister:
"I wish to change our culture" -> "We should break tradition and create our own way." (player custom tree)

 

[D3monic]

But Windy, custom tree are Swadians! He must emulate Khergit culture!