Megalopolis with the intention of centralizing political authority. Democracies Popular government was first established in the wealthy and populous Greek cities in Ionia. From this history the word and concept of "democracy" is derived. This synoecism was one of the primary causes of the Kyklos in ancient Hellas. Synoecism also occurred at Mantineia: in the fifth century, after its synoecism, it became a democracy; in the fourth century, it was again divided ("dioikismos") and an oligarchy formed. Later, more political upheaval caused another synoecism, thus instituting another democracy. This further occurred in the other Arcadian towns of Tegea and Heraia. In ancient Athens, the villages of Attica combined with the polis of Athens; consequently the "demos" and "polis" became identical in Athens and the former word assumed preference to denote the whole polity. A four tiered class system outlined by Solon on the basis of income either by the way of monetary wealth, agricultural production or otherwise was introduced in the 6th century as a way of distinguishing between citizens and the rest of the population. These four classes were again transformed under Kleisthenes into a further ten tribes as a way of further democratizing the political system and remove more power from the elite few. The general trend of Athenian power being transferred from a concentrated few to a greater and more evenly distributed percentage of the citizenry is a result of the transition from a loose group of villages to a collective singular polis. Representation of the landowning citizens helped represent the expanded interests of Athens such as navel, commercial, and agrarian ventures. The democratic nature of democracy in Athens helped the synoecism of such a populous center in Ancient Greece. The Delian League The Athenian Empire, also known as the Delian League, was a collection of Greek city-states largely based around the Aegean Sea which operated under the hegemony of Athens. This alliance initially served the purpose of coordinating a united Greek front against a perceived looming Persian threat against the Ionian city-states which bordered it. The members of the Delian League were made to swear an oath of loyalty to the league and contributed mostly monetarily but in some instances donated ships or other forces. It was also the case that many democratic members of the League owed their freedom from oligarchic or tyrannical rule to Athens. Because of this, Athens gained an overwhelming advantage in