A hijab simply states that the woman is a Muslim. No more, no less.

As for clothing being somehow related to civilization, that's ridiculous. Clothing came about as a means of protecting our weak, fur-less bodies from the elements. It had nothing to do with modesty, rather that came later as a result of the creation of religions who, for whatever bizarre reasons, started focusing on genitalia and sex as being "dirty."

Wearing less clothing is a sign that our technology has advanced to the point that we no longer require restrictive layers of clothing for protection against nature, it has nothing to do with civilization.