they were merchants and artisans part of an international diaspora spanning thousands of miles, it was really an economic role that they chose to assume. they weren't victims of a racist occupation like arabs in the west bank today.

some would say that they were kicked out of their homeland so it wasn't really a choice but there's actually no evidence that this ever happened. for one thing, jews have always lived in judea and there's no record of them being expelled from anywhere there except the city of jerusalem in the 2nd century by the romans after they tried another revolt. there was a huge jewish diaspora before that revolt and even before the 1st century revolt. the jewish diaspora was likely primarily a result of economic migration and subsequent success of jewish communities in certain economic roles as a diasporic community spanning many different lands.