What they don't tell here, but a german researcher told yesterday on radio, was that the initial conflict arose in the 90ies, when one large group of Ngogo chimpanzees raided a nearby group and killed all males. Thus they came later to that insanely large number of 200 members, which a decade later lead to this conflict with the two groups already seperated. Similar to the https://en.wikipedia.org/wiki/Gombe_Chimpanzee_War observed by Jane Godall.

Also missing is the Killer Ape theory of the sixties which led to the research that chimpanzees have much higher lethal conflict numbers than humans.

Also, this Ngogo group is highly researched, and many many films where made about them.