Came across this lecutre (or alternatively you can read the transcript) in a class from Yale on Moralities of everyday life:
A History of Violence Edge Master Class 2011
Some excepts:
"Believe it or not—and I know most people do not—violence has been in decline over long stretches of time, and we may be living in the most peaceful time in our species' existence."
"The fourth historical decline of violence has been called the "Long Peace." It speaks to the widespread belief that the 20th century was the most violent in history, which would seem to go against everything that I've said so far. Peculiarly, one never sees, in any of the claims that the 20th century was the most violent in history, any numbers from any century other than the 20th.
There's no question that there was a lot of violence in the 20th century. But take, for comparison, the so-called peaceful 19th century. That "peaceful" century had the Napoleonic wars, with four million deaths, one of the worst in history; the Taiping Rebellion in China, by far the worst civil war in history, with 20 million deaths; the worst war in American history, the Civil War; the reign of Shaka Zulu in southern Africa, resulting in one to two million deaths; the war of the Triple Alliance, which is probably the most destructive interstate war in history in terms of percentage of the population killed, namely 60 percent of Paraguay; the African slave raiding wars (no one has any idea what the death toll was); and of course, imperial wars in Africa, Asia and the South Pacific.
These remarks are all qualitative, meant to damp down the tendency to think that just because in Europe there was a span of several decades without war, that the world as a whole was peaceful in the 19th century as a whole.
What about genocide? The last couple of graphs plot what are called "state-based conflicts, where you have two organized armed forces fighting, at least one of which is a government. What about cases in which governments kill their own citizens? Again, there's a cliché that the 20th century was the Age of Genocide. But the claim is never made with any systemic comparison of previous centuries.
Historians who have tried to track genocide over the centuries are unanimous that the notion that the 20 th was "a century of genocide" is a myth. Frank Chalk and Kurt Jonassohn, their The History and Sociology of Genocide, write on page one, "Genocide has been practiced in all regions of the world and during all periods in history."
What did change during the 20th century was that for the first time people started to care about genocide. It's the century in which the word "genocide" was coined and in which, for the first time, genocide was considered a bad thing, something to be denied instead of boasted about.
As Chalk and Jonassohn say of ancient histories, "We know that empires have disappeared and that cities were destroyed, and we suspect that some wars were genocidal in their results. But we do not know what happened to the bulk of the populations involved in these events. Their fate was simply too unimportant. When they were mentioned at all, they were usually lumped together with the herds of ox and sheep and other livestock."
To give some examples: if Old Testament history were taken literally, there were genocides on almost every page; the Amalakites, Amarites, Canaanites, Hivites, Hitites, Jevasites, Midianites, Parazites and many other. Also, genocides were committed by the Athenians in Melos; by the Romans in Carthage; and during the Mongol invasions, the Crusades, the European wars of religion, and the colonization of the Americas, Africa and Australia.