I looked up the South African band. They mostly go by Xavleg. The full name is an initialism for "Acidic Vaginal Liquid Explosion Generated By Mass Amounts Of Filthy Fecal Fisting And Sadistic Septic Syphilic Sodomy Inside The Infected Maggot Infested Womb Of A Molested Nun Dying Under The Roof Of A Burning Church While A Priest Watches And Ejaculates In Immense Perverse Pleasure Over His First Fresh Fetus". They are a Christian band.
I was familiar with Overthrust from Botswana just to the north because Vice did an amazing article on them years ago (that fortunately has been captured by the Wayback Machine since the photos are gone on the live site):
I don’t discredit what Metallica contributed to the metal genre. Hell, I was once a hardcore Metallica fan. But since their heyday, many much better bands have appeared. And with actually good drummers.