This is an excerpt from The Destruction of Black Civilization by Chancellor Williams (available here). If you don't know a lot about African History and have only been taught Black history starting with slavery, you should definitely read this book.
The setting for the story described in the excerpt is Angola around 1622. The Portuguese were up to their usual nefarious business of rape, murder, and pillage, even against their own economic interest (slaves were worth more dead than alive, but the savages that they were, they couldn't help themselves and kept on with the mass murders).
It had gotten so bad that the Angolan King, who was a slave holder as well and a feeble ruler complicit in the destruction of his country, even had to put his foot down for fear of being sold into slavery himself. So he organized a resistance. However, the people, knowing the weakness of their king, were actually following his formidable sister, Ann Nzinga. The resistence was causing massive losses on both sides, and the Portuguese, tired of the many defeats they were suffering, sent a peace delegation. And that is where the story begins.
The peace conference was held at Luanda. The black delegation was headed by the country's ablest and most uncompromising diplomat, Ann Nzinga, not yet queen, but sister of the king - the woman power behind a weak king, and the one responsible for inspiring the people to continue the war of resistance when every hope was gone, unless she herself had become their last hope. But even before the peace conference began, and at the risk of wrecking it, the governor's Caucasian arrogance could not be restrained. He had decided on a studied insult at the outset by providing chairs in the conference room only for himself and his counselors, with the idea of forcing the black princess to stand humbly before his noble presence. He remained seated, of course, staring haughtily as she entered the room. She took in the situation at a glance with a contemptuous smile, while her attendants moved with a swiftness that seemed to suggest that they had anticipated this stupid behavior by the Portuguese. They quickly rolled out the beautifully designed royal carpet they had brought before Nzinga, after one of them went down on all fours and expertly formed himself into a "royal throne" upon which the princess sat easily without being a strain on her devoted follower. Yet she rose at regular intervals, knowing that the other attendants were vying for the honor of thus giving to these whites still another defeat. I gather from the different ways this incident is reported that the Western mind is unable to grasp its real meaning. Some historians saw it as a cruel and inhuman use of slaves, ignoring the fact that Nzinga's chief claim to fame was that she was the greatest abolitionist of slavery, that she herself had no slaves and, indeed, had not the slightest need for any. One reason might be that she was so much loved and even blindly followed by her people that is was believed that all would die, to the last man and woman, following her leadership. Such were the mean, not slaves, who gladly formed a human couch before the astonished Portuguese for their leader.