Why were the 7 hills that surround rome to the city's development?

The seven hills that are surrounding the city of Rome were of great importance for its development because they were excellent strategic defense points that enabled the Romans to protect their city much more easily than if it was surrounded by plains. When it came to the defense of the city, the seven hills were offering a big advantage to the Romans of always having the high position in the battles which is more often than not a crucial factor in winning or losing, thus the city was able to develop in relative security from being attacked or invaded.

i believe that the answer to the question provided above is that  establishing smaller ethnic communities within larger communities  gives more chance for people to know each other more but this might lead to the  conflict between groups.