Private Tribes or Sub-Tribes

I didn't know where to post this, but thought this might be the place to come.

Is it possible for someone to have a private Tribe? I've looked around and can't seem to find it.

One thought I had instead of having private tribes is to have Sub-Tribes or some better word than that. Maybe a Category.

Let's say I have a gaming community (I do LOL) and I want to have

• Officers [Group Read/Write, Global ---]
• Guild Masters [Group Read/Write, Global ---]
• World of Warcraft [Group Read/Write, Global Read]
• SW:TOR [Group Read/Write, Global Read]
• H1Z1 [Group Read/Write, Global Read]

etc... sub-tribes. Each of those tribes could have different permissions

This way, we could keep all of our Tribe content in-house and not have to create separate tribes for every single sub-group of our group.