" Beginning in 1901, Abdul Aziz and his small band of followers had set out on camels into the desert from his family’s exile in the neighboring emirate of Kuwait. Their aim was to restore the Saudi dynasty that had ruled part of the Arabian Peninsula twice before, in the eighteenth and nineteenth centuries. Over the next quarter century, Abdul Aziz would sweep across Arabia in alliance with ferocious fighters known as the Ikhwan. They were fierce adherents of an austere Islam that traced back to an eighteenth-century cleric, Muhammad ibn Abd al-Wahhab, who had sought to purify Islam, return it to its early roots, and cleanse it of heretics and foreign intrusion. The Islam of al-Wahhab became the faith of the new state, critical to integrating the different tribes into the reestablished Saudi realm. "
― Daniel Yergin , The New Map: Energy, Climate, and the Clash of Nations