Then you need to regionalize servers. Not sure why you haven't, most Asian/VN self segregate already.
The king feature will be available in the next update.
Regarding what you said a player needs to have the support of at least 10 cities to become a king. And it will change every 7 days so I don't think what you reported is an actual issue.
Moved to suggestions.
On server 61 house x has 8 cities alone already. So yea this system will be abused. They will always be blue king.
Same with red team on server 61 house AE-Vietnam have 8 cities. Both will have 10 cities by the time the king system comes into place.
Oh and I forgot to mention house x has a sister house named xx which also holds a few cities so yea they have more than 10 so they will always be king and the rest of us will become even more servants to their will than before.
A player must secure the support of at least 10
cities to become King. If multiple players breach this threshold, the player with the support of the most cities will become King.
At least, so if there are 20 cities they only have 50% and must try to convince others. This will create some more communication between players.