Pre-christan Slavs had no princes or kings in contemporary meaning as absolute rulers. We had 'rodowo plemienny' system which was very simple and effective.
When one tribe united with another one in family relationships, it was called the ‘ród’ and they were all relatives. When a community was formed in this way and was is self-managed, people from outside the family were not able to penetrate into this community. This kind of administration relates to the same family (Polish ‘rodzina’), tribe, ‘ród’, and “rody’ were united in the nation (Polish ‘naród’). This structure has been operating in Chechnya so far :
How it works? 10 neighbours living together for a long time and knowing each other very well gather and choose from among themselves the best host ('gospodarz') to be their representative. Then the top 10 hosts, responsible for 100 families, meet and elect the best representative. For 1,000 families are now 100 representatives, who choose ‘kniaz’ (prince), 'kniazie' select 'bojar', and 'bojary' select the king, who has the best qualifications. The function of the king was not inherited. The king could be removed when he didn’t fulfil his obligations. The whole nation was administrated by the best representative. Only unanimous decisions were taken in choosing the best option for the community. Women and older people had no voting right, only a consultative vote. If anyone witnessed the violation of social order, he was obliged to make every effort to remove the exemption, otherwise he was found guilty of being an accomplice to the crime. The most crucial factors in this system were that people self-managed each other, no stranger outside of 'ród’ (family) could penetrate the structures of administration and that the best of the best people came to the administrative power.
From what I know something like that functioned in ancient Poland. It was called 'kopne prawo', because decisions were made 'na kopie', i.e. on the mound or hill in a circle of representatives.