This concept of referring to your social network as a "Tribe" is quite an interesting one. It's the idea that surrounding yourself with a group of individuals of good quality and sharing a common interest can lead to further growth in yourself and your tribe members. Sir Ken Robinson in his book "The Element" argues that a synergy is created in tribes that leads to greater creation that anyone could accomplish individually.
Most of us are subconsciously selecting our tribe when we make decisions on who to spend our social time with. If you've ever done what I call "Facebook Cleaning" (removing people you're friends with but not sure why anymore) you're doing a form of tribal council from the TV reality show Survivor and managing your tribe. In our professional lives, having a tribe or tribes for ideas and interests can be important for growth and development too. Similar to a peer review process, if you can create a tribe of people and a place for them to communicate and share ideas, you can learn and contribute to a subject to help grow yourself and the others in your tribe.
I am in the process of creating a Network Learning Space (NLS) for gaming as a form of learning. I am using a website tool called Google+ Communities to create a place for individuals interested in the gamification of online learning to share and post ideas. It's not as good as an in-person round table discussion with the leading subject matter experts on technology, learning, game development and instructional design - but it's a start (and it's a lot cheaper).
Call it a clan, call it a network, call it a tribe, call it a family. Whatever you call it, whoever you are, you need one. - Jane Howard, American Journalist
In my efforts to grow my NLS, I called a friend of mine in game development to get an idea of what subjects and talking points would be worth a focus, then I called my colleagues who are in online training and asked the same thing. Rather than deciding for myself what are the best topics, I leaned on my peers for assistance. You bet they're in my tribe!
Another tip on tribe growth is from Seth Goldin, a marketing guru who suggests in his book "Tribes: We Need You to Lead Us" that helping others achieve their goals will inevitably create your tribe, and I agree that reciprocity is a powerful tool. This is why if you decide to create an NLS, ensure it can be collaborative.
Stay tuned, I am in the process of building out my NLS and while its success will hinge on a good tribe, it's also my responsibility to begin by populating the space with good quality content.