Up until the 1970's it was just a strip of stores on florida ave surrounded by farms.
I guess you can call Regur hardware and Chappie's bar a city
A city is a city regardless what establishments it may have or how many. It’s also a city regardless what definition you may choose to apply.
Hemet, in this case, is a city, or an 'incorporated municipality' if you wish. And has been one since 1910, or the last 100 years. That’s not ‘relatively new’ by any reasonable definition of the term.