OMAN and Yemen constituted a single geographical outcrop in the south of the Arabian Peninsula. They share natural and energy resources from the earliest times, starting with their location on the waterfront of southern Arabia and ending with the same demographic composition. Oman also controls the entrance to the Persian Gulf, which was a route for old commercial caravans and is now, in the modern era, a corridor for gigantic oil tankers. As for Yemen, it overlooks the entrance to the Bab elMandab that leads to the Red Sea. This important location for both Yemen and Oman has played a leading role in the path of human civilization since ancient times. The relations between the two countries go back to the third century BC (The Hellenistic era) This book relies on Arab and Foreign documents, the most important of which are the United Nations documents known as the Year Book and the British documents published as the Records of Oman, which they mainly benefited from, especially regarding the issue of the borders and, in particular, the tenth volume of these records dealing with the borders in Oman. As well as the Arabian Boundaries, research for this study relied on the Egyptian Foreign documents which addressed the Omani issue in the League of Arab States and Egypt's pioneering role in these issues. In addition, the reports of the political committee of League of Arab States on Arab countries, which clarified the role Yemen and its position on the Oman issue, further material was provided by the regular meetings of the League of Arab States.