> pertaining to or characteristic of a people, especially a group (ethnic group) sharing a common and distinctive culture, religion, language, or the like.
The inhabitants of a city usually share a common and distinctive culture (and the like.) You're using extremely narrow definitions of genocide as well as ethnicity. Both are vague terms.
http://en.wikipedia.org/wiki/Ethnicity
http://dictionary.reference.com/browse/ethnic
> pertaining to or characteristic of a people, especially a group (ethnic group) sharing a common and distinctive culture, religion, language, or the like.
The inhabitants of a city usually share a common and distinctive culture (and the like.) You're using extremely narrow definitions of genocide as well as ethnicity. Both are vague terms.