Regreg, becoming one of the most important bases of piracy in the region. In 1615 they also agreed to an alliance with Muhammad al-'Ayyashi, a religious warrior who started out as one of Moulay Zaydan's governors. As governor, Al-'Ayyashi had repeatedly attacked the Spanish at Mazagan (Al-Jadida). The Spanish persuaded Moulay Zaydan to rein him in and the sultan sent an army to stop him, at which point he fled north with his warriors. The Sous valley, meanwhile, had come under the leadership of 'Ali Abu Hassun al-Simlali in the town of Iligh since 1614. Abu Hassun fought with the forces of Moulay Zaydan's ally, Yahya ibn Abdullah al-Hahi, until the latter's death in 1626 left him uncontested in the Sous. He went on to conquer the Dra'a Valley and then as far Sijilmasa in the Tafilalt in 1631. The Dala'iyya, an important Sufi brotherhood in the Middle Atlas, became the most important opposition, especially under Muhammad al-Hajj, who ruled them between 1636 and 1668. He organized the Berbers of the region into a regular army which defeated a Saadian army sent by Muhammad al-Shaykh al-Saghir to subdue them in 1638. In 1641 he also defeated Al-'Ayyashi with the help of Al-'Ayyashi's former allies, the Andalusians in Salé, who had turned against him. The Dala'iyya occupied the area but allowed the pirates to continue operating. That same year they also captured Fez. Thanks to these victories, they established a new Berber state across a large area, and even conducted foreign relations, especially with the Dutch, with whom they signed a treaty in 1651. The last Saadian sultan was Ahmad al-Abbas, the son of Muhammad al-Shaykh al-Saghir, who inherited a reduced state from his father in 1655. As a child, he was placed under the tutelage of his mother's tribe, before being was assassinated and usurped by his maternal uncle in 1658 or 1659, bringing Saadian rule officially to an end. Eventually, a new Sharifian dynasty, the Alaouites from the Tafilalt, defeated all other factions to become the sole rulers of Morocco. The first effective Alaouite sultan, Moulay Rashid, conquered Marrakesh in 1668. Chronological summary 1510: Saadian chief Al-Qa'im recognized as leader of the Sous 1513: Al-Qa'im moves his base to Afughal, the burial place of Al-Jazuli 1517: Al-Qa'im dies; Saadian realm divided between his sons Ahmad al-'Araj and Muhammad al-Shaykh 1524 or 1525: Ahmad al-'Araj takes control of Marrakesh 1527: