In the 18th century, a pact between Islamic preacher Muhammad ibn Abd al-Wahhab and a regional emir, Muhammad bin Saud, brought a fiercely puritanical strain of Sunni Islam first to the Najd region and then to the Arabian Peninsula. Referred to by supporters as Salafism and by others as Wahhabism, this interpretation of Islam became the state religion and interpretation of Islam espoused by Muhammad bin Saud and his successors (the Al Saud family), who eventually created the modern kingdom of Saudi Arabia in 1932. The Saudi government has spent tens of billions of dollars of its petroleum export revenue throughout the Islamic world and elsewhere on building mosques, publishing books, giving scholarships and fellowships, hosting international Islamic organisations, and promoting its form of Islam, sometimes referred to as petro-Islam.