Which elite groups influence political decision making?

During the Middle Ages, the privileged strata of society had a huge influence on the implementation of political decisions. Initially, only boyars belonged to them. They were considered ancestral nobility and could influence the decisions of the ruler. The monarch had to reckon with the boyars, as they concentrated in themselves broad forces and opportunities. The second pillar was the military, who ensured the security and steadfastness of power. The clergy was also considered a privileged class. It influenced society spiritually.