The Asir Mountains[1] (Arabic: جِبَال عَسِيْر, jibāl ʿasīr; Arabic pronunciation:[d͡ʒɪbaːlʕasiːr] ('Difficult')) 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.[2]Sensu lato, they are part of the Sarawat Mountains,[3] 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.[4][5][6]
The region has the highest average rainfall of Saudi Arabia[citation needed] due to largely seasonal rain. Average rainfall can range from 600 millimetres (24 in) to over 1,000 millimetres (39 in) per year, in wet regions. The eastern plains and plateaus receive much lower amounts, from 500 millimetres (20 in) to below 100 millimetres (3.9 in) per year.[2]
The region's difficult terrain has helped preserve the region's unique biodiversity. Several new Myxomycetes fungi species have been discovered in the region, as have a variety of previously undiscovered plants.[7] Asir is also thought to be one of the last natural habitats of the Arabian leopard.[2][5][6] and also the Asir magpie, believed to be down to its last 135 pairs.[8]
Note: Mountains are sorted in alphabetical order, unless where it concerns ranges. The highest confirmed mountains in each country are indicated with 'HP', and those with the highest peak are indicated with 'HP', bearing in mind that in the UAE, the highest mountain and the mountain with the highest peak are different. Outcrops are indicated with 'OC', and outliers with 'OL', and anticlines with 'AC'. Volcanoes are indicated with 'V', volcanic craters with 'VC', lava fields with 'LF', and volcanic fields with 'VF'.