Around 1000 b.c. mainland Greece entered a  dark age  of limited achievements, but not so the Ionians, who developed an outstanding civilization.
The decline in Greek achievement opened an opportunity for the development of Ionian civilization. 
mnli hypothesis: The decline in Greek achievement opened an opportunity for the development of Ionian civilization.  premise: Around 1000 b.c. mainland Greece entered a  dark age  of limited achievements, but not so the Ionians, who developed an outstanding civilization.