Most of the key words commonly used to describe governments—words such as monarchy, oligarchy, and democracy—are of Greek or Roman origin. They have been current for more than 2,000 years and have not yet exhausted their usefulness. This suggests that humankind has not altered very much since they were coined. However, such verbal and psychological uniformity must not be allowed to hide the enormous changes in society and politics that have occurred. The earliest analytical use of the term monarchy, for example, occurred in ancient Athens, in the dialogues of Plato (c. 428–c. 348 bce), but even in Plato’s time the term was not self-explanatory. There was a king in Macedonia and a king in Persia, but the two societies, and therefore their institutions, were radically different. To give real meaning to the word monarchy in those two instances, it would be necessary to investigate their actual political and historical contexts. Any general account of monarchy required then, and requires today, an inquiry as to what circumstances have predisposed societies to adopt monarchy and what have led them to reject it. So it is with all political terms.
This article discusses the historical development of governments, primarily in the societies of the West.
Primitive government
Agricultural society
So long as humans were few, there was hardly any government. The division of function between ruler and ruled occurred only, if at all, within the family. The largest social groups, whether tribes or villages, were little more than loose associations of families, in which every elder or family head had an equal voice. Chieftains, if any, had strictly limited powers; some tribes did without chieftains altogether. This prepolitical form of social organization may still be found in some regions of the world, such as the Amazonian jungle in South America or the upper Nile River valley in Africa.
The rise of agriculture began to change that state of affairs. In the land of Sumer (in what is now Iraq) the invention of irrigation necessitated grander arrangements. Control of the flow of water down the Tigris and Euphrates rivers had to be coordinated by a central authority, so that fields could be watered downstream as well as farther up. It became
