Saudi Arabia, formally the Kingdom of Saudi Arabia (KSA), is a nation in Western Asia on the Arabian Peninsula. It is the fifth-biggest nation in Asia, the second-largest in the Arab world, and the largest in Western Asia, with a land area of around 2,150,000 km2 (830,000 sq mi). It is bounded on the west by the Red Sea, on the north by Jordan, Iraq, and Kuwait, on the east by the Persian Gulf, Qatar, and the United Arab Emirates, on the southeast by Oman, and on the south by Yemen. Bahrain is an island nation off the east coast of the Persian Gulf. Saudi Arabia and Egypt are separated by the Gulf of Aqaba in the northwest. Saudi Arabia is the only nation having coastlines on both the Red Sea and the Persian Gulf, and its landscape is mostly made up of dry desert, lowland, steppe, and mountains. Riyadh is the capital and biggest city. The nation is home to Mecca and Medina, Islam's two holiest cities.
Pre-Islamic Arabia, the land that comprises modern-day Saudi Arabia, was the home of various ancient societies and civilizations; Saudi Arabia's prehistory has some of the world's oldest signs of human activity. Islam, the world's second-largest religion, arose in what is now Saudi Arabia. The Islamic prophet Muhammad unified the inhabitants of Arabia and established a single Islamic religious state in the early seventh century. Following his death in 632, his adherents swiftly extended Muslim dominion outside Arabia, seizing vast and unprecedented swaths of land in a couple of decades (from the Iberian Peninsula in the west to portions of Central and South Asia in the east). Arab dynasties from modern-day Saudi Arabia established the Rashidun (632–661), Umayyad (661–750), Abbasid (750–1517), and Fatimid (909–1171) caliphates, among many others throughout Asia, Africa, and Europe.
Historically, Saudi Arabia was divided into four separate historical regions: Hejaz, Najd, and sections of Eastern Arabia (Al-Ahsa) and Southern Arabia ('Asir). King Abdulaziz established the Kingdom of Saudi Arabia in 1932. (known as Ibn Saud in the West). Through a series of victories that began in 1902 with the seizure of Riyadh, the ancestral seat of his family, the Al Saud, he unified the four areas into a single state. Since then, Saudi Arabia has been an absolute monarchy ruled by the king, the princes of the huge Al Saud royal family, and the country's traditional elites. Although the religious establishment's dominance has been considerably undermined in the 2010s, the ultraconservative Wahhabi theological movement within Sunni Islam has been characterized as a "predominant characteristic of Saudi society." Saudi Arabia maintains its Basic Law as a sovereign Arab Islamic state, with Islam as its official religion, Arabic as its official language, and Riyadh as its capital. Saudi Arabia is frequently referred to as "the Land of the Two Holy Mosques" in reference to the two holiest shrines in Islam, Al-Masjid al-Haram (in Mecca) and Al-Masjid an-Nabawi (in Medina).
Petroleum was found on March 3, 1938, and was quickly followed by many further discoveries in the Eastern Province. Since then, Saudi Arabia has risen to become the world's second-biggest oil producer (after the United States) and largest oil exporter, with the world's second-largest oil reserves and sixth-largest gas reserves. The kingdom is classified as a high-income economy by the World Bank, with a very high Human Development Index, and is the only Arab nation to be a member of the G20 major economies.
The kingdom spends 8% of its GDP on defense (the most in the world after Oman), making it the world's third largest military spender behind the US and China, as well as the world's top weapons importer from 2015 to 2019, getting half of all US arms shipments to the Middle East. According to the BICC, Saudi Arabia is the world's 28th most militarized nation, with the region's second-best military equipment, behind Israel. By the late 2010s, there have been repeated requests to restrict military supplies to Saudi Arabia, owing primarily to suspected war crimes in Yemen and, more recently, the killing of Jamal Khashoggi. The state has been chastised for a number of reasons, including its role in the Yemeni Civil War, alleged sponsorship of Islamic terrorism, and its poor human rights record, which has been characterized by the excessive and often extrajudicial use of capital punishment, failure to adopt adequate measures against human trafficking, state-sponsored discrimination against religious minorities and atheists, and antisemitism, as well as its strict interpretation of Sharia law.
Saudi Arabia is regarded as a regional as well as a medium power. The Saudi economy is the biggest in the Middle East and the world's eighteenth largest. Saudi Arabia also boasts one of the world's youngest populations, with over half of its 34.2 million people under the age of 25. Saudi Arabia is a member of the Gulf Cooperation Council, as well as the United Nations, the Organization of Islamic Cooperation, the Arab League, the Arab Air Carriers Organization, and OPEC.