I've read a few different biographies of Muhammad, and they all talk about one tribe being "stronger" or "weaker" than another. For example, in Medina, the Jewish tribes were originally stronger, but by Muhammad's day, the Jewish tribes had become clients / proteges of the stronger Arab tribes. There is also some talk of Muhammad's clan, the Hashim, having fallen on hard times before Muhammad was born.
What does it mean, in particular, in practical terms, for one tribe to be stronger or weaker than another? Or to become stronger or weaker? Military might? Wealth? Or maybe a charismatic leader who is good at making alliances with other tribes? Or something else entirely?
Edit: I don't know how to apply modern politics to this question. Specifics much appreciated.