Pentecontaetia Achievement

[Never Wong]

Hi guys I was looking up all on the internet for guides to do this achievement but I cant find much. Just how do you do this in 50 years? You need to conquer some lands from the big guys around (Macedon, Thrace, Phrygia) as tiny Athens. I tried rebelling from Phrygia immediately but only managed to capture half of the needed lands b4 time runs out.