Arab Union
In terms of internal structure, every confederal state is composed of two or more constituent states, that are referred to as "confederated states". In regard to their political systems, confederated states can have republican or monarchical forms of government. Those that have republican form (confederated republics) are usually called "states" (like states of the American Confederacy, 1861-1865) or "republics" (like republics of Serbia and Montenegro within the former State Union of Serbia and Montenegro, 2003-2006). Those that have monarchical form of government (confederated monarchies) are defined by various hierarchical ranks (like kingdoms of Iraq and Jordan within the Hashemite Arab Union in 1958).