The Cathars were a medieval Christian sect with a neo-manichaean philosophy, a heretical gnostic sect, holding that matter was evil and only spirit was good; this was a fundamental challenge to the notion of incarnation, central to Roman Catholic theology. It originated from a reform movement within the Bogomil churches of Dalmatia and Bulgaria calling for a return to the Christian message of perfection, poverty and preaching. They became known as the Albigensians as it gained many adherents in the city of Albi and surrounding area in the twelfth and thirteenth century.