In addition to u/gingerkid1234's answer, one of the contributing factors of such discrimination dips into questions of human psychology rather than history. Jewish populations of the world rarely if ever integrated into the societies they inhabited, which automatically sets them apart, and humans are, it seems, fundamentally equipped psychologically to be wary of those that are different, consequently making it easy to dislike or even hate certain groups. We can see the same set of processes in play with discrimination against Roma populations, although the Roma's situation is exacerbated by their still-as-yet semi-nomadic culture in a world of sedentary nation-states.

You may be interested in this answer of mine on the subject.