My focus will be on city building so I want to play the Neran

Who knows? Most kingdoms are holding that information to themselves. But for me personally,

1. To'resk
2. Janoa
3. Kypiq (only because people hate them so I want to play one kind of).

I know Blackheart is explicit about it. Some of the others have expressed preferences. You can make some educated guesses if you read their postings and visit their Discord channels.

Highly up to change at this point, they haven't even released guides to each tribe. Neran and Brudvir are literally the only tribes that have both their location described and their building style shown. Also, Biomes haven't even been described and what kind of flora and fauna that exists in them is about as long as a college kids grocery list. (very small)

There is a reason everyone thinks Brudvir and Neran are ideal for them or that Brudvir have all the cool animals, because we literally no nothing about what life will LOOK like when it comes to the other tribes or what actually exists in the other biomes.

If it's an attempt by the devs to keep surprises in the game, cool, but they will in the end push more people to bet on the only areas actually fleshed out and fully described.

I only know that MOST of the kingdoms are vying for northern kingdoms. The only kingdom directly vying for anything different that I've heard about is Blackheart with the Dras.

I imagine the only other tribe on the list for some kingdoms would be Janoa for the more war/pvp centered kings.

But, like the above said, you can more or less find out that list by checking out their discords. Although, they will all preface with "we are still debating that"

I personally think that the most successful kingdoms will have a large variety of tribes living in them though a kingdoms goals will cause the tribe popularity to vary wildly. If I had to take a guess at which would be the most popular based on kingdom style. (Militaristic kingdoms having janoa, Trading kingdoms having To'resk, etc.)

The reason I think this is because a kingdom style will invite certain types of players. those players will be not only more attracted to the kingdom that matches their play style but also the tribes that match it as well.