Achaean League Coinage
About B.C. 370 several cities on the southern side of the Corinthian Gulf banded together as a means of defence against Macedonian ag- gression, and the coins issued by them are usually referred to by the above name.
The monogram of the League was AX, which is frequently found on the coins.
The League increased in power circa B.C. 280, and eventually included all of the Peloponnesian cities, some of which, how- ever, also struck independently. It ceased B.C. 146 with the constitution of the Ro- man province.
Source: Frey's Dictionary (American Journal of Numismatics, Vol. 50, 1916)