What was the first all-Jewish city and when was it founded?

Answer 1

Cities - No.

The Jews have never had a provision a la Saudi where only Jews are permitted entry to a certain city or region. Judaism provides for "Stranger Among Them" or "Ger Bitokham" (גר בתוכם). Therefore, there has never been an exclusively Jewish city.

However, most ghettos and other Jewish neighborhoods in the Medieval Period (especially in Europe) were exclusively Jewish because both non-Jews and Jews wished to live separately. Similarly, in the Arab World, there were a number of Jewish tribes which lived in their own encampments outside of the larger metropolises of that era. These, though, are not considered cities. Finally, there were a number of kibbutzim and moshavim in Israel that have always been selectively Jewish or only attracted Jewish membership. These also are not Jewish cities because a kibbutz or a moshav is never large enough to be an urban center.