Re: Religious Tolerance (Shias and Sunnis)
It was not exactly Saudis; it was the movement under Muhammad bin Abdul Wahhab who made reforms in the Islamic society of Saudi Arabia. According to him people of Hijaz were involved in the acts of shirk and innovations (bid’aat) and so he made relations with the family of Sauds and used their power to spread his views in the kingdom.
I will try to do a research on Muhammad bin Abdul Wahhab and his movement in Saudi Arabia.
As for the former rulers of Hijaz, they promoted shirk the way other rulers promoted shirk in the rest of the Muslim lands including the subcontinent. If I am not wrong the grave worship, and shrine polytheism emerged from Persia and shias and disguised shias in the form of Sufis promoted such ideas among Muslims.