While Alexander's generals were fighting for land, the Greek cities were left untouched. Instead of forming one union, all the cities started fighting each other out of jealousy for each other's land. As the quarrels became more bitter, the Greeks created the Achæan and Ætolian leagues.
The Achæan league was made of twelve small towns, and was under the control of the Greek Aratus. When Aratus was young, his father had rebelled against a tyrant who ruled their city and had been killed along with the rest of his family. The child, who was seven, fled to the tyrant's sister who hid him and took care of him. After growing up, the kid remembered his father's death, so he led a bloodless revolt against the tyrant which ended with the tyrant being banished and the Achaean league's birth.