The most rapid decline in violence both domestic and internationally has come in the past two centuries.
On an international level, the peak was half a century ago and the decline has been very rapid. It coincides with rapidly growing international trade.
On the domestic level crime rate and violent crimes have been decreasing steadily for 200 years which parallels the rapid rise of industrial commerce.
Think about the story of Romeo and Juliet. Two families at war. Think about the modern Arab and African world where family warfare continues unabated.
When someone has to either sell you something or get a job, both required in a commercial society, that person has to learn to cooperate with strangers. That is commerce and that is the reason for the socialization by our society that has the side benefit of decreasing interpersonal crime.
Of course some people get jobs with the government. They nevertheless need some socialization that has the side benefit of decreasing violent crime.
When you give thanks at dinner for your food at Christmas tonight and tomorrow, it may also be worthwhile being thankful to commerce for the relatively safe and peaceful society we live in. If you live in one of the most dangerous cities in America, you are highly aware that there is very little commerce in your city.