All of these people are Black. The Tuaregs and the Arabs are lighter skinned Blacks then the rest, and they have more Caucasoid features, but these are all Black people we are talking about here. In fact, Tuaregs are ~86% Black by genes and only 14% Caucasoid, about the same as US Blacks. Arabs may be the lighter, but the distinction between an Arab and a Black in this part of the world is not strong. An Arab is more someone who is a pastoralist and speaks Arabic. A Tuareg speaks the Tuareg Berber language and is a pastoralist. The Blacks probably speak an African language, are darker and look more African and may be agriculturalists.
But what matters more is if you were born into slavery or not. Slavery has been going on forever in the Sahel. There are still 200,000 slaves in Mali. There are also many in Mauritania and Niger. Food is so scarce at times that some slaves enter into bondage voluntarily just to get something to eat. The slave masters are very cruel to their slaves, treating them worse than animals. Although slavery is illegal in Mali, the law is hardly enforced.
What is interesting is that with the coming of radical Islam in the form of the Islamist jihadis, the slavery issue got worse. Ta Tuaregs and Arabs largely supported the Islamists and they took advantage of the coming of the jihadis by enslaving their Black neighbors, reclaiming old slaves, or enslaving their Black workers. Now that the French ran the Al Qaedists out of Timbuktu, the slaves have been freed, but there are now deep wounds that will take ages to heal. The Blacks here are very angry at what the Arabs and Tuaregs did to them, and they will not forget soon. This is a very brutal part of the world.
In some ways, this mirrors the genocide going on in Darfur, with the pastoralist Arabs committing genocide against the agriculturalist Africans. In the same way, both are Blacks, but the Arabs speak Arabic, are lighter, taller, thinner and have more Caucasoid features. The Blacks are darker, speak African languages and have been African features. The Arabs have always treated the Blacks with contempt in Sudan even before the Darfur genocide.
The war against South Sudan was similar except that it was a religious war. The South Sudanese were more African, spoke African languages, and tended to be Christians and animists. The northern Arabs committed mass murder on the infidels of the South. A favorite way of killing the infidels was crucifying them on a makeshift cross. Similarly, radical Islam was used by the northern Arabs to radically Islamicize their cause and once again, it seemed the extra dose of Islam made the Arabs that much more racist against the Blacks.
It is important to note that this war was seen as a jihad against the infidels by the radical Islamist regime in the North. Their idea was the that Southern infidels should be given the choice of converting to Islam or dying. There were in fact many forced conversions and similar to the situation in Mali, many South Sudanese, especially women, were kidnapped and taken as slaves to the North, where they served in their Arab master’s homes. The slavery often had sexual overtones as the women were made to serve as sex slaves.
As you can see, we are dealing with a Sahelian regional phenomenon here. But note also the deep connections between Arabs and the enslavement of Blacks in this part of the world. Arabs have been enslaving Blacks forever. Saudi Arabia only outlawed slavery in 1963. There was a report recently of a castrated Black slave being offered for sale by a wealthy Gulf Arab. The ad selling the slave appeared on Facebook.