Which political system is run by a group of noble families or wealthy members of society?

Oligarchy is the political system that is run by a group of noble families or wealthy members of a society. The term Oligarchy was first used by the great Aristotle for describing the powers that were held by a very small and highly privileged group. These people often misused their powers and treated the people under their rule very poorly and also used them to satisfy their selfish needs. It has been commonly seen that the rulers that believed in Oligarchy actually selected people on herediterary basis and not based on merit.