This kind of relationship, one between the producers and the maintainers (or rulers) is a highly unequal and dependent one. Historically, internal differentiation has usually preceded the arrival of state structures, and while that alone has not necessarily been enough to push every society through the evolution from primitive to complex, it remains that specialization is a prerequisite for the emergence of a ruling class—rulers specialize in power. A division of labor encourages a society to differentiate, and heighten the material and intellectual culture of that society.