Yasir Qadhi seems to admit that taking sex slaves as a result of war by early Muslims was permissible. He admits that this is controversial in Islam and that he gets lots of questions about this issue. The issue is mentioned in the Qur’an and the Hadith. The Qur’an refers to it as the woman captives of war, “that your right hand possesses”. look at all the verses in both the Qur’an and Hadith that mention this. The details are very graphic (and almost pornographic), more so in the Hadith than in the Qur’an. If I understand him correctly, he even says that most of the people of the Abbasids (the people of the Abbasid Caliphate era in Iraq), and Ottomans (Uthmaniyeh) – I think this is what he means; they were children from the taking of the wives who were conquered. I remember several Iranian former Muslims admitting to me that, going all the way back to the Arab invasions of Persia (636 AD to 900s AD), his ancestors were probably the offspring of a Persian woman who was captured by the conquering Arabs. Many Iranians admit to being half or 1/4 Turkic in their ethnicity. The Turks also did lots of Jihads when they came from Central Asia. (Seljuks, later Ottomans, etc.) It seems that in the early Islamic Jihads and wars, the men were killed and the women were taken captive and they had many children from these captured women, and the result was massive changes in the ethnic make-up of the peoples of lands that Muslims conquered.