Athens was the principal town in the 'county' of Attica. The term usually employed is that of city-state, although, strictly speaking, Athens was neither quite a city nor a state. It was a polis which effectively controlled Attica, and certain other city-states beyond its borders. The key factor in any consideration of class and social differentiation in Athenian society was that of citizenship. The total population during the Classical period is quite unknown; scholars, as usual, differ considerably in their estimates. Wealth counted for a great deal, but breeding was still important. Most Athenian males were small farmers, artisans and labourers. Commerce, especially for the upper classes, was still not quite respectable. Sparta had a complicated – and some might think, 'untidy' – four tiered system of political organization. It consisted unusually, of a monarchy with two hereditary kings who held office simultaneously, somewhat like early Republican Roman consuls.