Gives me a great idea for a gameplay element. I think that any society with hungry people will have violence. So I guess when town people go hungry for any reason, e.g. not being able to exchange their goods for grain, or not being able to save grain for themselves, violence will break out.
A 100% peaceful colony sounds utopian.
But I still doubt it was a war-ridden province though. I guess they just had some basic safeguards against any hostile attacks. They were definitely not threatened enough to raise an army, so it seems to make sense.
The no of immigrants would have to be carefully monitored. Ideally, you should allow a small no of immigrants, put then into orientation programmes - apprenticeship etc and wait for them to get conditioned to the city. Immigration is change - how much change you can handle is upto the player. If you allow a large no of immigrants in, or allow a fresh batch too soon(before the previous batch is acclimatized), you end up with a big change that adversely affects the city.