Question, I'd make a relative small house which more or less governs a single city. It would be on the island between GreviousKhan and Abefroeman's domain. But would anyone mind if they were the literal money makers (aka the minters) of the empire? Controlling vast amount of funds themselves. Money is alwasy required for whatever you do so they are still very powerful. And the previous emperor, with his love for boats, heavily loaned from my family (putting the crown into somewhat of a debt with my guys, a debt they want to see repaid).