Zulu were a war like nation engaged in successful conquering of SAfrican tribes yes. Just like many many others before throughout the world.
If they had learnt to build the infrastructure of civilisation like others before then sub Saharan culture could have had one united pan- culture and developed just like others before it.
But we destroyed that - apparently doing them a favour
Japan shows an excellent example of how to absorb technological advances without getting wiped out - and offers an alternative to your rather insulting White conquer or self destruction theory.