What geographic features of Greece encouraged the independence of Greek city-states?

The country's mountainous terrain, many isolated valleys, and numerous offshore islands encouraged the formation of many local centers of power, rather than one all-powerful capital. Another key factor influencing the formation of city-states rather than kingdoms was the Mediterranean.

Source:

https://www.pbs.org/empires/thegreeks/background/9b_p1.html#:~:text=The%20country's%20mountainous%20terrain%2C%20many,than%20kingdoms%20was%20the%20Mediterranean.

what class is this for i can then

1. i forgot 2. he was gay 3. they killed a lot of the population 6. they rode horses and had swords we have guns and tanks