...because white people had not yet developed that level of technology.
But nobody was holding the zulus back, dude. They could have colonized Mars 300 years ago and eaurope could not have done anything about it.
Anyway for some mysterious reason they didn't.
This ridiculous tangent...as amusing as it is...simply continues to highlight the fact that white people did not become dominant because of slavery.
Literally everyone had slaves... technology is the real reason whites became dominant.