I've created a (semi-isolated) evil area of the campaign world which has outlawed magic. The reason: I don't know!

I'm interested in three sets of suggestions:

1) what could have caused magic to be declared anathema? It happened before the kingdom turned evil, about 300 years ago.

2) There is an order of priests of the most important god whose responsibility is to ferret out magic use. Actually, they use arcane as well as divine magic to do this. Is there an evil prestige class out there that would fit this motif?

3) I need ideas for some good city adventures/motifs that take advantage of this concept. There are a few other facts that might help: the culture is vaguely roman, women are definitely second class citizens, and slaves are common (as are lizard-man types as said slaves).

Right now, I'm fleshing out the campaign area before starting a new campaign in a few months.