I have heard some people making this claim but I don't know much about Slavery to make a comparative analysis. So, is this really true or just bad history?
While focusing more on the practice of castration and the role of eunuchs, this answer by /u/caffarelli does talk a bit about the Islamic slave trade, which should help with your question!
Follow up question: I've heard that US slavery is the only system that considered slavery hereditary (all children of slaves are also slaves automatically), how accurate is this?
Did this type of generational continuation add a sense of hopelessness/difficulty in gaining freedom that wasn't present in other slavery practices?