Why was ancient greece divided into a collection of city-states?

Correct answer choice is :

When the Greek nomadic clans occupied land to settle on and become agricultural, the tribes took pieces of river plains surrounded by mountains, building a castle and then a city as the center of the tribal patch. A city protected its region from others, and so the independent city-state became the foundation of the Greek world. When the cities sent out their growing excess population which could not be supported a city's limited land, they, in turn, took a patch of land around the Mediterranean and more cities grew up, ultimately numbering a pair of thousand.

it provided for selection of government employees through competitive examinations. it also made it unlawful to fire or demote covered employees for political reasons or to require them to give political service or payment, and it set up a civil service commission to enforce the law.

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