What Changes did the greeks make during the Greek "Dark Ages" (1100 BCE- 850 BCE)?

-1100-850 is a time of great changes in Greece; we have the advent of the Dorians in Greece,the destruction of Mycenaean civilization,the development of Protogeometric pottery and the appearance of Greek settlements in Asia Minor and Greek islands.Do to the invasions lead by the 鈥淪ea People鈥?some Greeks started to become more nomadic, many things such as the creation of art were slowed down in order to put all recourses into military.