Barbarians!

[Tim White]

Barbarians need work. For one thing, make them real barbarians, make them look different, and be much more diffacult to get rid of. In all of history, nearly entire civs were destroyed because of barb. Make them like a tiny civ, with mini sttlements here and there, depending on what level of barb. activity you choose.

[rremus]

There were some related treads, about Minor Civs and Nomads. Did you read those? They're interseting...