Every attempt towards periodization is to some degree arbitrary: the beginning and end of the Middle Ages, for instance, cannot be fixed to a year, because development is a continuous process.

To some degree any periodization is a matter of convenience, and it should be accepted as such.

If we adopt a political system of periodization, we might say that around 500 B.C. the unified feudal state of the first period of Antiquity came to an end and the second, a period of the national states began, although formally, the feudal system continued and the national states still retained many feudal traits.