Megafauna outside of Africa were very sensitive to the introduction of Humans into their territory

The Holocene extinction includes the disappearance of large land animals known as megafauna, starting at the end of the last Ice Age. Megafauna outside of the African continent, which did not evolve alongside humans, proved highly sensitive to the introduction of new predation, and many died out shortly after early humans began spreading and hunting across the Earth (many African species have also gone extinct in the Holocene, but —with few exceptions— megafauna of the mainland was largely unaffected until a few hundred years ago). These extinctions, occurring near the Pleistocene–Holocene boundary, are sometimes referred to as the Quaternary extinction event
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Holocene extinction - Wikipedia