Some clues :
Douglas P. Fry : Pacified Past
Azar Gat : Warfare as an Ancient Feature
Robert L. Carneiro : Complexity and State Formation
Was the 20th century one of the most violent in human history ? (with two world wars and numerous other conflicts) ?
i also like the documentary series : “The Ascent of man” from the BBC in 1973 by Jacob Bronowski.
We live in the information age, so called because our ability to gather, store and share information has developed to the point where those changes define this age. We notice them specifically because the changes stand out due to their speed and reach.
Warfare and violence has generally always had a downwards trajectory, in the modern age its our information about it which is unprecedented.