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.
After the Persian Wars, the Delian League was formed as a mutual-defense pact and it was based on the sacred island of Delos during its first 25 years of existence.
[1] While no major conflict occurred, there existed a form of cold war between Greece and Persia punctuated by incidents such as diplomatic moves and countermoves, threats, and raids, particularly along the border that separated the territories of the two powers.
[2] At its peak, membership swelled to about 200 and, in exchange for Athenian protection, each paid phoros in talents of silver while the more powerful members such as Samos, Chios, and Lesbos supplied warships as their tribute.
According to Aristotle, the very first phoros ("that which is brought") was assessed by Aristeides a couple of years after the battle of Salamis.