The study deals with the role of Saud bin Abdul Aziz in the relations between Saudi Arabia since its establishment by the late King Abdul Aziz Al Saud in 1932 and the Yemeni Mutawakkil Kingdom until the end of 1962. The study covers part of the reign of King Abdul Aziz Al Saud from 1932 to 1953, where Prince Saud bin Abdul Aziz was crown prince from 1933-1953 and part of the reign of King Saud bin Abdul Aziz 1953-1962. As for the Mutawakkala Kingdom of Yemen, the study includes part of the reign of Imam Yahya Hamid al-Din (1932-1948), the period of Imam Ahmad ibn Yahya Hamid al-Din (1948-1962), and the period of his son Imam Muhammad al-Bader (1962). The importance of studying the relations between these two countries is due to the fact that they are the two largest Arab states in the Arabian Peninsula, and their status in the Arab, Islamic and international world, in addition to the fact that Saudi Arabia and Mutawakil are the two countries with full independence in the Arab world. Other Arab countries were either linked to treaties with colonialism or directly colonized, in addition to the fact that the Arabian Peninsula was the cradle of Arabism and the source of Islam.