The government does not conduct census on religion but some sources estimated the percentage of Shia in Saudi Arabia to 10% and others to 15% of approximately 20 million natives of Saudi Arabia. The modern Kingdom of Saudi Arabia was formed in 1932 by the House of Saud, who are followers of a strict interpretation of Sunni Islam known as Wahhabism or "the Wahhabite mission". Followers of the Wahhabite mission—who dominate religious institutions, courts and education of the kingdom—believe Muslims should return to the interpretation of Islam found in the classical texts, the Quran and the Sunnah. They also believe that Muslims who seek intercession from holy men, such as the imams revered by Shia, are not true Muslims. While attempts to force conversion of Shia have been infrequent, Shia face severe discrimination in Saudi Arabia.
While Saudi Arabia has only existed since 1932, an earlier Al Saud state (Emirate of Diriyah) clashed with the Shia. Ibn Abdul-Wahhab believed that Shia "imported into Islam" the practice of building mosques on graves, a practice he considered un-Islamic. He referred to Shia as Rafida (rejecters), a name his followers have continued to use.
In 1802, the Saud-Wahhabi alliance waged jihad (or at least qital, i.e. war) on the Shia holy city of Karbala. There, according to a Wahhabi chronicler `Uthman b. `Abdullah b. Bishr:
Muslims [Wahhabis referred to themselves as Muslims, not believing Shia to be Muslims] scaled the walls, entered the city [...] and killed the majority of its people in the markets and in their homes. [They] destroyed the dome placed over the grave of al-Husayn [and took] whatever they found inside the dome and its surroundings [...] the grille surrounding the tomb which was encrusted with emeralds, rubies, and other jewels [...] different types of property, weapons, clothing, carpets, gold, silver, precious copies of the Qur'an."
Al-Hasa, the main Shia area of what is now Saudi Arabia, was conquered by Saudi forces in 1913. The initial treatment of Shia was harsh, with Shia religious leaders compelled to vow to "cease observance of their religious holidays, to shut down their special places of worship and to stop pilgrimages to holy sites in Iraq." Wahhabi ulama also "ordered the demolition of several Shia mosques" and took "over teaching and preaching duties at the remaining mosques in order to convert the population." However, within a year Al-Saud emir Ibn Saud permitted the Shia to expel the Wahhabi preachers and to hold private religious ceremonies led by the Shia religious establishment "without interference."