James C. Scott has an excellent review in the LRB of Jared Diamond’s recent book The World Until Yesterday: What Can We Learn from Traditional Societies?.
There is plenty of violence in the world of hunter-gatherers, though it is hardly illuminated by resorting to statistical comparisons between the mortality rates of a tiny tribal war in Kalimantan and the Battle of the Somme or the Holocaust. This violence, however, is almost entirely a state-effect. It simply cannot be understood historically from 4000 BC forward apart from the appetite of states for trade goods, slaves and precious ores, any more than the contemporary threat to remote indigenous groups can be understood apart from the appetite of capitalism and the modern state for rare minerals, hydroelectric sites, plantation crops and timber on the lands of these peoples.
Scott’s The Art of Not Being Governed: An Anarchist History of Upland Southeast Asia is useful to think with about Colombia.