It depends on what time you mean. Tribal life based on hunter-gathering or herding domestic grazing animals tended to be more or less stateless. Agrarian life tends to have cities and states. The latter has more concentrated populations that support nastier diseases, and herders do too.
If you are a microbe infecting a hunter-gatherer person, you might need to wait a year before that person comes close to people outside his own group of 50-300 people. It doesnt pay to multiply to high concentrations that will mess up your host. But if there are plenty of people all contacting each other from Paris to Belgrade and Moscow, you might as well just "go for it".
At the same time states reduced violence using policing, and execution of the guilty (typically, torture-execution). Before that, there was only "vandetta law", and nearly the most immoral thing was to fail to take bloody revenge when wronged, thus showing that your family or group could be harmed with impunity. States could not project force very far, and they typically did not have enough wealth to form large professional armies, so the amount of carnage from war was rather limited. Or, if they used citizen militia instead of professionals, as seen in classical Greece, those citizens could not spend very much *time* fighting, so that also limited killing.
Thus, more disease, less violence. This was probably the way of things in europe once grain agriculture spread there from the middle east. This took kind of a long time. SE europe was doing this 11,000 years ago, but my ancestors in the northwest were hunter-gathering until more like 5000 years ago. It is not clear to what degree those hunters were replaced by my grain growing ancestors, or rather *were* the ancestors and adopted farming themselves.
In tribal life there was probably far more violence, with 20-60% of all males dying in violence, which is far bloodier on a per-person basis than even europe in the 20th century was. At least that was the case in Yanomamo and New Guinea and other tribes studied by outsiders. A few scholars like Brian Ferguson think this started only after agriculture and states introduced these people to war-like practices, crowded them onto remnant territories, etc. I suspect he is romanticizing hopelessly, but I have to admit I am not closely familiar with the dispute.
Most amerindians lived tribally, and as mentioned before, had almost no infectious diseases. The only ways to die, when you have no predators, are to fight, or starve, or die of virulent diseases. Most people start fighting rather than starve. There were of course a few very interesting amerind civilations in meso and south america. The Inca empire collapsed mysteriously long before 1492. I think(?) the Mayans were the only literate state in the americas. Three or so of their books now exist. Tragically, there were hundreds or thousands of other books, but almost all were burned by conquering europeans, because they were considered a possible focus of opposition to christian proselytization. (Sadly the great Library of Alexandria was often damaged in war and then may have been similarly destroyed by muslim conquerers. And protestant europeans destroyed some of the incomparable sacral art of the Roman church. It happens a lot.)
Tribal violence tended to consist not of battles, but of you and me and some other guys hiking over to the next town, killing some guy that we find working or foraging by himself, and then clearing out. Or we might kill multiple people in a twilight massacre at dawn. The first of those two modes is also done by chimps, and its possible there has been this kind of war the entire time since we diverged from them 5 million years ago. Guys like Ferguson tend to say that this started only because humans disturbed and crowded the chimps. Chimps also kidnap fertile females, like tribal humans do, and state-dwelling humans also do the same thing.
Chimps do this because 5 chimps can kill one enemy without risk to themselves, because three of them can hold the victim down. In general, almost all animal species refrain from fighting brutally. They fight lightly, and the one who can see he is inferior will then submit. It is not worth the risk of being wounded by serious fighting. Suppose one robin kills another, getting wounded in the process, which probably does happen very, very rarely. The dead bird's territory will be carved up by adjoining birds. But the bird that did the work and took a mortal risk will probably get the least benefit; being wounded, he wont be able to contend well with other males. At a cost to himself, he handed a benefit to his competition. Thus, animals fight "for real" mainly in those species in which a harem of multiple females is available to the victor. Only then does such behavior increase their fitness, making a "profit". One female is not worth the fight. For example, elephant seals routinely fight lethally against other adults, as do gorillas. Chimps, in addition to war against enemy groups, also carry out violent coups in which a new coalition of three or so males takes over. The top three chimps in a social group of 100 or so father almost all the offspring. But they tend to be executed by the new up and comers, a few years later.
You can see how these sort of facts help lead me to a conservative worldview. While we did get a lot nicer after 1800 when we were no longer hungry, I think that human nature does not automatically produce a well-functioning civilization, and that it can only function well when we give our loyalty to the institutions and traditions that can help correct and guide our not-exactly-divine nature.
