Subordinated Kingdoms?

[Bronnen]

This is the first time i've gotten this. In this game, i'm byzantia.

I've convinced two kingdoms to hand over the crowns to me, and I have 4 vassals. One of my vassals is almost as huge as Byzantia is (Genoa has 15 kingdoms while i have 18) and the other 3 are small 1-3 province kingdoms.

Now, what the hell does that mean?

Apparently I earn 1 gold from this subordinated kingdom

[Kuno of Gersenau]

This is something only occurs when you play with Byzantia (or Nicaea in High Period). Byzantia is seen as the head of the Orthodox Christianity, therefore all Orthodox kingdoms without a patriarch have to pay a certain tribute to them. That's as well the reason why you can't get a patriarch if you play with Byzantia.