The Rwanda genocide was the Hutu "people" genociding the Tutsi "people".

I say "people", because both of those demographics are almost entirely artificial and were created by the ruling class in the late 19th century based mostly on the criterium of "Do you own cattle?", and then exploited and the split enlarged first by german colonizers and then by the belgians. The belgians then made it official by printing it on their mandatory ID cards.

And of course, both the Germans and the Belgians preferred the wealthy, cattle-owning tutsi minority over the poorer hutu majority. And when the white colonizers left, the hutu's decided to grab some power back... with genocide.