In those small, isolated areas, the Serbs formed their basic territorial and political units. Each unit comprised a small geographical area, usually a river valley or a basin with the villages in it, bounded by the surrounding hills. The unit was called "župa" and the local chieftain who administered it was called "župan". Župans, in turn, were subordinated to the "knez" or prince ("archon", ἄρχων in Greek; "dux" in Latin). The knez was the supreme elder and ruler of the entire people while župans were intermediaries between him and the people. As in the other parts of the early medieval Europe, Serbian "state" didn't mean by default a rule over the territory, but over the people. So, the Serbian political organization included only areas which were populated by the Serbs, excluding the vast uninhabited areas in between. That way, the borders of the "state" can't be accurately determined.