The main achievement of this reform was to replace with new units the former four Ionian tribes into which Attica had been traditionally divided. Cleisthenes' new organisation included ten tribes, each of these composed of three trittyes picked up in three distinct territorial regions. Since one of the reform's major effects was to undermine the hereditary control of local aristocrats, Cleisthenes was later to be regarded by many as the founder of the Athenian democracy.
Bouchard, Elsa. "Cleisthenes' reform". The Literary Encyclopedia. First published 01 March 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=11177, accessed 19 September 2014.]