A History of Violence
Emphasis for (or against) ancient warfare is absent until about 20,000 years ago. The 10,000 years between then and agriculture are ambiguous. Skeletons collected from some parts of the world are nearly free of evidence of violent death at human hands (but remember only injuries to bones are preserved). Skeletons from other regions show a high incidence of human caused violence (embedded spear and arrow points), and probable evidence of massacres on the scale of entire bands.