The twelfth and thirteenth centuries saw the development both of active, widespread movements that challenged the official theology and hierarchy of the Roman Catholic Church, and the development of an apparatus, the Inquisition, to systematically identify and extirpate heretical communities. The earliest sect to pose such a challenge was that variously called the Cathars, Albigensians, Manichaeans (from a similarity to a quasi-Christian 4th century sect originating in Persia) and Good Christians.  Concentrated in Languedoc in southwestern France, this sect was the subject, successively, of exhortation and evangelization, a twenty year military crusade (1209-1229) under Pope Innocent III, and a systematic legal campaign facilitated by Dominican friars using a proceeding taken from Roman criminal law known as Inquisitio. The latter was much more successful than either exhortation or military action and was also used against the Waldensian or poor Christians, Jews posing as Christian converts, and sorcerers. Inquisitors gathered evidence of heresy through interrogation of suspects and witnesses concerning their belief systems and practices. A believe that heretics were cunning and deceitful created a bias against a finding of innocence. Examination of the detailed records left by some inquisitors reveal that the popular perception of torture and burning large numbers of people at the stake, reinforced by Protestant anti-Catholic polemics, is based on some of the most extreme examples, and that more typical penalties for heretics who agreed under oath to the tenets of the Catholic church were public penance, economic sanctions, and imprisonment. Because heretical movements were deeply rooted in the social life of the population and in family structure, the Inquisition had a profound effect on society in the areas where it was active. The Pope most responsible for initiated formal inquisition using the Mendicant orders of the Franciscans and Dominicans was Gregory IX.