Kingdom of Saudi Arabia To understand the history of the Kingdom and its political, economic and social development, it is necessary to realize that Islam, which permeates every aspect of a Muslim's life, also permeates every aspect of the Saudi Arabian state. The Arabian Peninsula, including Kuwait, Qatar, the United Arab Emirates, the Kingdom of Saudi Arabia -- has supported agricultural, herding and hunting cultures for thousands of years. Because they lived on important ancient trade routes, the ancestors of today's Saudi Arabians were influenced by such varying civilisations as Mesopotamia, Egypt, Greece, Rome, Byzantium, India, Persia and China. The Holy Qur'an was revealed to the Prophet Mohammed in the western Arabian cities of Makkah and Madinah beginning about AD610. The birth of the new faith of Islam was an important historical event. Inspired by their new religion, the Arabs expanded from Arabia, spreading Islam and the Arabic language as far west as the Atlantic Ocean and as far east as central Asia. Muslim civilisation remained vigorous for centuries, providing stability and advancing human knowledge when most of western Europe was in a state of chaos and superstition known to historians as the Dark Ages. In the 13th century, the Mongol invasions dealt a devastating blow to the Arabs' eastern lands and their empire began to decline. Saudi Arabia is a monarchy. The government is based on the Sharia, the sacred law of Islam, which is interpreted according to the strict Hanbali rite by the learned religious elders, or ulama. Saudi Arabia is divided into 13 administrative districts. Large cities elect their own municipal governments. Towns and villages are governed by councils of elders. Saudi Arabia is bounded on the north by Jordan, Iraq, and Kuwait; on the east by the Persian Gulf and Qatar; on the southeast by the United Arab Emirates and Oman; on the south by the Republic of Yemen; and on the west by the Red Sea and the Gulf of Aqaba. The country's borders with Yemen and the United Arab Emirates are not precisely defined. Saudi Arabia has an area of about 2,240,000 sq km (about 864,900 sq mi). The capital and largest city is Riyadh. The population of Saudi Arabia is composed mainly 82 % of Arabs whose ancestors have lived in the area for many centuries. A substantial minority of 13% consists of Yemenis and other Arabs who came to Saudi Arabia after the 1950s because of the economic opportunities the country afforded. Nomads, known as Bedouins, make up a declining proportion of the population, and the number of settled residents has also decreased. The climate is extreme heat and aridity are characteristic of most of Saudi Arabia. The Arabian Peninsula is one of the few places in the world where summer temperatures above 48oc (120o F) are common, while in winter frost or snow can occur in the interior and the higher mountains. Precipitation is sparse throughout the country. Annual rainfall in Riyadh averages 100 mm (4 in) and falls almost exclusively between January and May; the average in Jeddah is 61 mm (2.4 in) and occurs between November and January. Because of the general aridity, Saudi Arabia has no permanent rivers or lakes. Saudi Arabia is a large Middle Eastern nation that ranks as one of the world's leading producers of petroleum. Much of the country consists of vast deserts where few people live and little or nothing grows. But beneath the sand and rock of Saudi Arabia lie some of the largest petroleum deposits in the world. In 1902 Abdul al-Aziz Ibn SAUD captured Riyadh and set out on a 30-year campaign to unify the Arabian peninsula. In the 1930s, the discovery of oil transformed the country.