Our hunter-gatherer phase, for instance, of course included some instances of violence, but it was nothing like we have seen in the modern era. Humans generally found it self-defeating to engage in tribal warfare once the longer-range spear had been invented. If you click on my link below, you can see some research of even more recent era of Japanese history where there was also relative peace. Mind you, that's a 12,000 year period. When someone picks out a comparatively tiny span of time, like 800s - 1800s, and declares that this is in some way a just comparison to millennia and millennia of relative peace, he isn't making a strong argument. Also, keep in mind, how the specter of atomic/nuclear annihilation is/is not figured into this equation. Like Jordan Peterson, he's another of these legitimate academics who have found a lot of acclaim and wealth by becoming prominent on YouTube and by writing popular books. I love popular books, but they need to be good ones and sometimes these guys sacrifice good research for commerciality. (Amusingly, Pinker has the exact opposite take on identitarianism that Chris has, but Chris finds him useful in citing him to reinforce his "Things just keep getting better and better!" thesis.)
As for the Psychology Today article, we don't emphasize enough the positive social markers associated with "tribalism." That term carries almost entirely negative connotations these days, and I'm guilty of employing it only in that way much of the time. That said, the homogeneity often correlated with that tribalism brings with it higher levels of social solidarity and less anomie.
Link: https://cassiopaea.org/forum/threads/study-of-ancient-japanese-hunter-gatherers-suggests-warfare-not-inherent.41326/