Stumbled upon this at wikipedia:
[en.wikipedia.org]

A mamluk (Arabic: مملوك (singular), مماليك (plural), "owned"; also transliterated mameluk, mameluke, mamaluke, or mamluke) was a slave soldier who converted to Islam and served the Muslim caliphs and the Ayyubid sultans during the Middle Ages. Over time, they became a powerful military caste, and on more than one occasion they seized power for themselves, for example ruling Egypt in the Mamluk Sultanate from 1250-1517.