In 1744 Emir Muhammad Ibn Saud, aided by the Muslim Wahhabi sect, began expanding his holdings in central Arabia. Saud's descendants continued expansion and conquered the Hejaz during the first decade of the 19th century. During 1812–18, however, Egyptian forces of the Ottoman Empire retook the Hejaz. From that time until the early 20th century, the Saud family fought Ottoman forces and rival families for control of central Arabia. By the mid-1920's Ibn Saud ruled the Nejd and Hejaz. In 1932 he renamed the entire region the Kingdom of Saudi Arabia.

Important dates in Saudi Arabia
c. 570 Muhammad, prophet of Islam, was born in Mecca.
c. 1500 The Saud family established control over a small area around Dariyah, near present-day Riyadh.
1500's The Ottoman Empire gained control over Hejaz and parts of Asir.
Mid-1700's The Wahhabi movement, which urged strict observance of Islamic laws, spread across most of Arabia. The Saud family supported and helped spread the movement and took over a large part of the Arabian Peninsula.
1891 Tribal leaders and the Ottomans gained control of most of Arabia. Leading members of the Saud family fled in exile.
1902-1932 Abd al-Aziz ibn Saud, an exiled Saudi leader, conquered the Najd, Hasa, Asir, and Hejaz regions and formed the Kingdom of Saudi Arabia.
1933 The Saudi petroleum industry began.
1967 Saudi Arabia supported Egypt, Jordan, and Syria in the Six-Day War against Israel.
1973 Saudi Arabia stopped or reduced oil shipments to some Western nations after another Arab-Israeli war broke out.
1975 Faisal, king of Saudi Arabia since 1964, was assassinated. He was succeeded by his half brother Khalid.
1982 Khalid died and was succeeded by his half brother Fahd.
1991 Saudi Arabia and a coalition of other nations defeated Iraq in the Persian Gulf War of 1991.
2005 Fahd died and was succeeded by his half brother Abdullah.

In 1933 an American company was permitted to explore for oil. Huge reserves were discovered in 1938, and after World War II the oil fields were developed, bringing the country vast wealth. Saudi Arabia supported other Arab nations against Israel but remained friendly with the United States.

Under King Faisal, who took the throne in 1964, a program was begun to raise the standard of living and to industrialize so that eventual depletion of oil reserves would not weaken the economy. Faisal was assassinated in 1975 by one of his nephews. One of Faisal's half brothers, Khalid, became king, and another, Fahd, became crown prince and responsible for the day-to-day administration of the country. Upon Khalid's death in 1982, Fahd was chosen king.

Following the revolution that overthrew the shah of Iran in 1979, relations between Iran and Saudi Arabia deteriorated, largely because of Iran's attempts to impose its fundamentalist religious views on its neighbors. In 1987 a clash between Iranian pilgrims and Saudi security forces in Mecca resulted in the death of more than 400 persons, mostly Iranians.

Following the invasion and seizure of neighboring Kuwait by Iraq in August, 1990, Saudi Arabia joined 36 other nations—principally the United States, Great Britain, France, Egypt, and Syria—in a coalition against Iraq. During January-February, 1991, the coalition forces, operating out of Saudi Arabia, freed Kuwait of the Iraqi occupation.

After the war, U.S. military forces remained in the country. However, their presence was opposed by Islamists who considered it a religious affront. In 1996, Islamic terrorists attacked a U.S. military barracks at Khobar with a truck bomb, killing 19 servicemen.

King Fahd died in 2005 and was succeeded by Crown Prince Abdullah, his half brother.