North African Muslims did start the Atlantic slave trade.
They were also quite active in the white slave trade, raiding across the Mediterranean.
And before the Muslims, the Egyptians held slaves, until Moses delivered them from bondage 3500 years ago.
But you cannot say that in Australia, lest you offend their very fragile snowflake sensibilities.
Actually, they did not start the Atlantic slave trade, but they did supply it. The first Europeans to explore the coast of sub-Saharan Africa were Portuguese sailors who discovered slave trading posts along the coast put there by North African Muslims. The Portuguese thought, “Gee these would come in handy for our colony in Brazil.” And so it began. Then the Spanish, and next the British followed along.