One thing that was on the radar for Bronze Age, but I never got around to, was the idea of Cultural Assimilation. The idea was that after long contact, your tribe could start to absorb elements from other tribes. The Hummites could learn how to tame chickens from the Masklings, or the Shontu could learn how to make Bronze from the Hummites. I never was able to get around to that then, but I can now. Unlike Bronze Age, in Bronze Age: Tribes the factions aren't as rigid. The higher level, abstract, approach means that varying features of a tribe is a lot less developer intensive than it would be previously. 

Here you can see the starting Humittle culture. Instead of a wholly bespoke set of structures and units like they were in Bronze Age, now they are a collection of cultural traits.

 Artisans - A cultural heritage of skilled craftspeople give the Humittes bonuses to industry related production

 Heirs of Atlantis - The Humittes claim to be the heirs to the legendary city of Atlantis (not entirely sure what this will do yet)

 Citybuilders - The Humittes are skilled city builders, and can build larger cities without suffering hygiene penalties.

 Nobility - The Humittes have a distinct noble caste, who perform different work than the commoners, and have different requirements

 Warrior Nobility - The Humitte nobility have a warrior tradition, giving access to more powerful recruits from noble pops

This is just the initial set of traits for the Humitte culture. My plan is for the player (and AI) to eventually be able to add or remove traits from cultures during the course of a game, creating sub-cultures. You won't be limited to one culture per region either, but can have as diverse, or homogeneous of a cultural makeup as you'd like. Regardless of culture, though, the Humittes will remain human (well, Atlantean technically), just as the Shontu, Naqada, Yarani, or any other human culture.

Masklings will have their own cultures as well, sharing the traits available to the Humittes.

Pops

The way you will interact through the game is by assigning pops. These are discrete units of population, representing a thousand or so people. Pops can be assigned to a single tile, and will work that tile to produce resources. Usually, each tile can only comfortably hold a single pop. You will be able to build developments on tiles, which will change the resource production available, but you will always need a pop present to work the tile.

I'll go more into detail on Pops next time, as I start development on them and the basic gameplay mechanics.