Sorry, I did not mean to discount the impact of tribalism. It is certainly a significant issue in East Africa (I can't speak for other areas). The history of the USA shows that even affluent western countries suffer from the Us vs Them mindset.

That said, I do believe that poverty is the more significant issue. Increased development generally correlates with stronger government [1], and with better access to government. When this happens, disputes are more likely to be resolved through the legal system.

I'm not an expert on the interaction between tribalism and warfare in developing countries, so don't think I'm trying to claim infallibility. This is just what I believe to be true.

[1] I say correlates, because I can't say that development causes stronger government. It could be the other way around

EDIT: Okay, now it's my turn to ask: what did I say wrong? Would you like to discuss it, rather than just downvoting?.

I didn't downvote. Even relatively rich countries outside of Africa like Mexico, Chile, and Panama have very high violent crime rates, but mostly among the poor (in Panama anyway, in Mexico I suspect there's a lot more drug related violence.) So poverty is definitely a big issue, but tribalism plays a big role too, e.g. bloody civil wars and ethnic cleansing. A lot of violence in South Africa is either race related or tribal. So it's not that you're wrong, it's just that the picture is more complex than just poverty alone.

First world countries have an equally long history of the same hatred, fear, discrimination and constant warfare. In general terms, it only lessened when a large proportion of the population could move out of poverty and feel reasonably secure about their future.

You don't have to look far to see how easy it is to revert to barbaric and uncivilized behaviour and standards when that sense of safety and security is put at risk.