How did I meet these city states?
Solution 1:
There are at least three ways this can happen:
- Another city-state asked you to destroy them
- That city-state declared war on you (because you went to war with their ally)
- You encountered a unit of the city state
It looks like Hanoi at least you are at war with.
Solution 2:
If you know a citystate that wants you to wipe that unmet citystate out, you get to meet them for free.
Solution 3:
As HorusKol states. I did met another city state because their ship visited me.