Federal states

A federation (also known as a federal state) is a political entity characterized by a union of partially self-governing states or regions under a central (federal) government. In a federation, the self-governing status of the component states, as well as the division of power between them and the central government, is typically constitutionally entrenched and may not be altered by a unilateral decision of either party, the states or the federal political body. Alternatively, federation is a form of government in which sovereign power is formally divided between a central authority and a number of constituent regions so that each region retains some degree of control over its internal affairs.

The governmental or constitutional structure found in a federation is known as federalism. It can be considered the opposite of another system, the unitary state. Germany, with 16 Bundesländer, is an example of a federation, whereas neighboring Austria and its Bundesländer was a unitary state with administrative divisions that became federated, and neighboring France, by contrast, has always been unitary.

Federations are often multiethnic and cover a large area of territory (such as Russia, the United States, India, or Brazil), but neither is necessarily the case. The initial agreements create a stability that encourages other common interests, reduces differences between the disparate territories, and gives them all even more common ground. At some time, that is recognized and a movement is organized to merge more closely. At other times, especially when common cultural factors are at play such as ethnicity and language, some of the steps in this pattern are expedited and compressed.

Several ancient chiefdoms and kingdoms, such as the 4th-century BC League of Corinth, Noricum in Central Europe, and the Haudenosaunee Confederation in pre-Columbian North America, could be described as federations or confederations. The Old Swiss Confederacy was an early example of formal non-unitary statehood.

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