The Ridda Wars (Arabic: حُرُوب ٱلرِّدَّة‎), or Wars of Apostasy, were a series of military campaigns launched by the Caliph Abu Bakr against rebel Arabian tribes during 632 and 633, just after the death of the Islamic Prophet Muhammad.  The rebels' position was that they had submitted to Muhammad as the prophet of Allah, but owed nothing to Abu Bakr.

military campaigns sanctioned by the Latin Church in the Middle Ages

The caste system in India is the paradigmatic ethnographic example of caste. It has origins in ancient India, and was transformed by various ruling elites in medieval, early-modern, and modern India, especially the Mughal Empire and the British Raj. It is today the basis of educational and job reservations in India. The caste system consists of two different concepts, varna and jati, which may be regarded as different levels of analysis of this system.