Saudi Arabia and Iran are two big countries in the Middle East and two hostile countries. The tension between the two countries has a long history. As early as the fifth century BC, during the Persian Empire, there were contradictions and conflicts between different factions in this area. Saudi Arabia, located in the middle of Arabian Peninsula, is the Sunni country with the largest oil reserves in the world. Iran, located in the southwest of the Middle East, is a Shia country, with a land area and population in the forefront of the Middle East. There are obvious differences in religious beliefs and cultural backgrounds between the two countries. The contradiction between Iran and Saudi Arabia can be traced back to 1400 years ago, when two branches of Islam appeared, namely Sunnis and Shiites. Sunnis believe that Muhammad's successor should be an elected leader, while Shiites believe that Muhammad's successor should be a member of his family. This difference has led to many conflicts and struggles in history.