the ulema have historically been led by the al ash-sheikh, the country's leading religious family. the al ash-sheikh are the descendants of muhammad ibn abd al-wahhab, the 18th-century founder of the wahhabi form of sunni islam which is today dominant in saudi arabia. the family is second in prestige only to the al saud (the royal family) with whom they formed a "mutual support pact" and power-sharing arrangement nearly 300 years ago. the pact, which persists to this day, is based on the al saud maintaining the al ash-sheikh's authority in religious matters and upholding and propagating wahhabi doctrine. in return, the al ash-sheikh support the al saud's political authority thereby using its religious-moral authority to legitimize the royal family's rule. although the al ash-sheikh's domination of the ulema has diminished in recent decades, they still hold the most important religious posts and are closely linked to the al saud by a high degree of intermarriage.