Saudi Arabia (/ˌsɔːdiː əˈreɪbiə/, /ˌsaʊ-/), officially known as the Kingdom of Saudi Arabia (KSA), is an Arab state in Western Asia constituting the bulk of the Arabian Peninsula. With a land area of approximately 2,150,000 km2 (830,000 sq mi), Saudi Arabia is geographically the fifth-largest state in Asia and second-largest state in the Arab world after Algeria. Saudi Arabia is bordered by Jordan and Iraq to the north, Kuwait to the northeast, Qatar, Bahrain, and the United Arab Emirates to the east, Oman to the southeast, and Yemen to the south. It is separated from Israel and Egypt by the Gulf of Aqaba. It is the only nation with both a Red Sea coast and a Persian Gulf coast, and most of its terrain consists of arid desert or barren landforms.
The area of modern-day Saudi Arabia formerly consisted of four distinct regions: Hejaz, Najd, and parts of Eastern Arabia (Al-Ahsa) and Southern Arabia ('Asir). The Kingdom of Saudi Arabia was founded in 1932 by Ibn Saud. He united the four regions into a single state through a series of conquests beginning in 1902 with the capture of Riyadh, the ancestral home of his family, the House of Saud. Saudi Arabia has since been an absolute monarchy, effectively a hereditary dictatorship governed along Islamic lines. The ultraconservative Wahhabi religious movement within Sunni Islam has been called "the predominant feature of Saudi culture", with its global spread largely financed by the oil and gas trade. Saudi Arabia is sometimes called "the Land of the Two Holy Mosques" in reference to Al-Masjid al-Haram (in Mecca), and Al-Masjid an-Nabawi (in Medina), the two holiest places in Islam. The Kingdom has a total population of 28.7 million, of which 20 million are Saudi nationals and 8 million are foreigners. The official language of Saudi Arabia is Arabic.
Petroleum was discovered on 3 March 1938 and followed up by several other finds in the Eastern Province. Saudi Arabia has since become the world's largest oil producer and exporter, controlling the world's second largest oil reserves, and the sixth largest gas reserves. The kingdom is categorized as a World Bank high-income economy with a high Human Development Index, and is the only Arab country to be part of the G-20 major economies. However, the economy of Saudi Arabia is the least diversified in the Gulf Cooperation Council, lacking any significant service or production sector (apart from the extraction of resources). The country has attracted criticism for its restrictions on women's rights and usage of capital punishment. Saudi Arabia is a monarchical autocracy, has the fourth highest military expenditure in the world, and in 2010–14, SIPRI found that Saudi Arabia was the world's second largest arms importer. Saudi Arabia is considered a regional and middle power. In addition to the GCC, it is an active member of the Organisation of Islamic Cooperation and OPEC.