Slavery under Islam dates back to Mohammed. It was interrupted by European efforts from British and French authorities during the colonial period, which also provided non-Muslims, such as Christians and Jews with the equal rights denied to them by Islam, and later by American pressure, which forced the Saudis to officially abolish slavery in 1962, though unofficially the practice continues.
The Islamic State has officially brought back slavery in a very big way.
The new UN report states that, “The number of people currently being held in slavery by ISIL numbers approximately 3,500. Those being held are predominantly women and children and come primarily from the Yezidi community, but a number are also from other ethnic and religious minority communities.”
That means non-Muslims. For the most part this is about rape since the majority of slaves are women and children, not young men. ISIS has been known to murder elderly non-Muslim women.