This has nothing to do with the article. African inter tribal wars are frequent, and very well documented.

I would actually make the argument that colonial times pacified the continent, partly thanks to increase of standard of living, modern governance, but also because it made certain inhuman practices illegal (human sacrifices, slavery etc)

However, i believe that forcing these tribes to live together within the same country was a huge mistake. You have the same dynamics in the middle East.

Do you think it is normal that the fronters in Africa are straight lines, with angles... ?

Don t you think they create a country between ethnies that never exist before ? or split etnie that was a nation ?