The Asir Mountains is a mountainous region in southwestern Saudi Arabia running parallel to the Red Sea. It comprises areas in the Region of 'Asir, but generally, it also includes areas near the border with Yemen. The mountains cover approximately 100,000 square kilometres (40,000 sq mi) and consists of mountains, plains, and valleys of the Arabian highlands. Sensu lato, they are part of the Sarawat Mountains, defining the latter as the mountain range which runs parallel to the Tihamah throughout the western portion of the Arabian Peninsula, particularly the western parts of Saudi Arabia and Yemen.

The Sarawat Mountains, also known as the Sarat in singular case, is a part of the Hijaz Mountains in the western part of the Arabian Peninsula. In a broad sense, it runs parallel to the eastern coast of the Red Sea, and thus encompasses the mountains of Fifa', 'Asir and Taif. In a narrow sense, the Sarawat start in Taif city in Saudi Arabia, and extend to the Gulf of Aden in the south, running along the entire western coast of Yemen, in what used to be North Yemen, and extend eastwards into part of what used to be South Yemen, thus running parallel to the Gulf of Aden.