A kingdom doesn’t only consist of villages, but usually also a couple of oases. In Travian 5, these oases no longer belong to particular players. Instead, they are part of the kingdom they are located in.
In Travian 5, you will play as either king or governor. Both roles have advantages and disadvantages. You can crown yourself king at any time or join one of the kingdoms around you as a governor.
In the video from Gerhard (2 of 5 in the series) he talks about the kingdom system which is new in Travian T5.