mountains have elevations ranging from a few hundred meters to the highest point in the country and the Arabian Peninsula, Jabal An-Nabi Shu'ayb, which is above sea level, within the Harazi subrange of the Sarawat. The range of elevation is thus from sea level to , and among the countries in the Arab world, it is the one with the second highest high point, after Morocco's high Jbel Toubkal. The Yemenis used the elevation of their homeland to stay isolated for thousands of years with foreign trade conducted only when the Yemenis wished to go to the coastal areas. The mountains are young, jagged peaks that are known to rise from an elevation of a few hundred meters to well over . The mountains can be separated into a western and central highland. The western highlands have peaks reaching around , with relatively fertile soil and sufficient and plentiful rainfall. The central highlands is more like a plateau of about , with rolling hills, small knolls, and some very prominent peaks, but is still relatively more elevated. Less rainfall can be seen in this region, but the summer months give enough to sustain crops. Climate Temperatures are lower in most of Yemen than in most of the Arab world due to most of the country being at high elevation. Rainfall is higher at higher elevations. The highlands enjoy a temperate, rainy summer with an average high temperature of and a cool, moderately dry winter with temperatures occasionally dipping below . The climate of the Tihamah (western coastal plain) is tropical; temperatures occasionally exceed , and the humidity ranges from 50 to 70 percent. Rainfall, which comes in irregular heavy torrents, averages annually. In Aden the average temperature is in January and in June, but with highs often exceeding . Average annual rainfall is . The highest mountainous areas of southern Yemen receive from of rain a year. Some areas of the western highlands, most notably Ibb and Ta'izz, receive from about of rain each year. The capital, Sana'a, receives around a year, it is not uncommon for the northern and eastern sections of the country to receive no rain for five years or more. The Wadi Hadhramaut in the eastern part of Yemen is arid and hot, and the humidity ranges from 35 percent in June to 64 percent in January. Yemen has the most fertile land in the Arabian