Societies like the Mongols, Iroquois, and Scythians were not matriarchies as much as societies where wise women's advice was heeded. In these cultures women's opinions were officially accepted in political decisions more than they were elsewhere, though women had extensive influence even in outright patriarchies (the Ottoman empire was sometimes ruled by the sultan's wives if the sultan was incapable). What these cases show is that women holding powerful positions did not stop fighting or scheming.
Why I would not call these societies matriarchies is that political power was in practice shared between men and women. Matriarchy implies that men are relatively powerless, which was not the case and has not been the case even in societies which are very respectful of women and allow polygamy by both sexes (the Mosuo, for example). There has never been a society, or at least not one recorded, where men were widely oppressed by women, or men held no power at all.
The article about hunter gatherers, or how Pinker's choice of tribes were not hunter gatherers at all, suggests that our past may be closer to non violent bonobos than violent chimpanzees, but that seems unlikely given how things have turned out; inventing warfare at the start of agriculture seems somewhat unlikely if we had not done it before, and it seems much more likely that bonobos are just an exception to the generally violent nature of apes and we are one of the generally violent species. There are very few hunter gatherers left, but it seems very unlikely that those hunting spears never turned on members of another tribe.