Ibn Tumart urged his followers to arms in open revolt against the Almoravids, to fulfill the mission of purifying the Almoravid state. In 1122, or shortly thereafter (c. 1124) he founded a ribat at Tinmel (or 'Tin Mal', meaning (she who is) white), in a small valley of the Nfis in the middle of the High Atlas. Tinmel was an impregnable fortified complex, which would serve both as spiritual center and military headquarters of the Almohad rebellion. It is during this period that he wrote a series of monographs on various doctrines for the instruction of his men. These disparate works were later collected and compiled in 1183-84, on the order of the Almohad caliph Yusuf ibn Abd al-Ma'mun (later translated in French in 1903, under the title Livre d'Ibn Toumert.)