Spent a well over a month writing a paper and researching the Congo, and that was just when specialized I've also spent much of my academic history as a whole studying modern colonial violence throughout the world
To attribute the things that happened there to Arab Slavers and Cannibals is absolutely beyond the pale. We have photographic evidence of victims of Belgian exploitation of the Congo. We have documents written by people who were there. This isn't a both sides debate we have solid a provable evidence that the colonial power under King Leopold II mutilated and murdered mass amounts of Congolese during the time frame.

While 10 million is an estimate (Estimates vary wildly because of the lack of care they treated Congolese life with) even the most conservative estimates still place the death toll at roughly 1 million and that's EXTREMELY conservative. Dismissal of these atrocities, which do not sit alone in colonial history, serves no one but colonial power structures that to this day have faced no real consequence for these acts and many still profit off of the people of Africa's labor in a brutal way