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Athens.
Attica.

The Cleisthenic reforms of 508/7, which firmly established democracy at Athens, imposed a new division of Attica into ten tribes, each of which constituted a new political and military unit, but included citizens from each of the three geographical regions of Attica—the city, the coast, and the inland. Enrollment in a tribe (according to heredity) was a mandatory prerequisite for citizenship.

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Delphi.

As usual in ancient Athenian affairs, politics and religion came hand in hand and, after due consultation with Apollo’s oracle at Delphi, each new tribe was assigned to a particular hero after whom the tribe was named; the ten tribal heroes are thus known as the eponymous (or name giving) heroes.