Its territory corresponded with that of the current municipalities Acharnes, Dionysos, Kropia, Lavreotiki, Marathon, Markopoulo Mesogaias, Oropos, Paiania, Pallini (except the municipal unit Gerakas), Rafina-Pikermi, Saronikos, Spata-Artemida and Fyli.
It spread rapidly with the help of intense winds, and intensified into the northwestern edges of Greater Athens, including both Ano Liosia and towns and villages such as Fyli, near Thrakomakedones, Pyli and both Skoura and Schimatari north of the mountain.
It was founded in 1938 and named after Thrasybulus, an ancient General who used Fyli as his base to liberate Athens from Sparta.