Shia Islam in Saudi Arabia
The Saudi government does not conduct a census on religion or ethnicity, but some sources estimate the Shia population in Saudi Arabia to make up around 10-15% of the approximately 20 million natives of Saudi Arabia. Saudi Arabia's Twelver Shia community, the Baharna, is primarily concentrated in the country's Eastern Province, chiefly Qatif and Al-Ahsa.
Source: Wikipedia — Shia Islam in Saudi Arabia (CC BY-SA 4.0)