Besides democratic and communist governments, there are other kinds of political systems such as Feudalism, Fascism and Theocracy. Feudalism is de-centralized political system during middle ages. The land is held in exchange for service and obedience is rendered in exchange for protection. Thus, society is hierarchically ordered. Most of medieval Kingdoms in Europe and Japan had Feudal system.
Fascism is totalitarian-dictatorship rule in the name of nationalism or certain political agenda. Germany, Japan and Italy during the World War II had this system.
Theocracy is system that government is ruled by religion. Thus, the religious leader or religious institution has more power and authority than government. Under this political system, religion is the most important criteria to make all decisions in a society. Generally speaking, Iran is belonged to Theocracy.