How to -- 4th century BCE setting

[Kiero]

I have mainly seen sources from the southern European area, but do not have any at hand.

I remember that estimates for Denmark is typically around 500.000, and I have seen one for Norway at 200.000-300.000, but that is rough estimates, and could likely vary depending on various factors. So they could be of by a rather large margin.

OK, but why look only at sparsely-populated northern Europe? Southern Europe and the Levant had much higher population densities than this, being better suited to support large numbers of people and often featuring more centralised states.