Phoros

In Ancient Greece, phoros (Greek: φόρος) was the name for the membership dues paid to Athens by the members of the Delian League, formed to offer protection from Persian forces. It could be paid in military equipment (such as triremes) or money, most usually the latter. Consequently, a great deal of funds was paid to Athens for the purpose of military initiatives. Athens increased its military forces, resulting in its becoming a dominant and wealthy power.