Unification of Saudi Arabia

The unification of Saudi Arabia was a military and political campaign in which the various tribes, sheikhdoms, city-states, emirates, and kingdoms of most of the central Arabian Peninsula were conquered by the House of Saud, or Al Saud. Unification started in 1902 and continued until 1932, when the Kingdom of Saudi Arabia was proclaimed under the leadership of Abdulaziz, known in the West as Ibn Saud, creating what is sometimes referred to as the Third Saudi State, to differentiate it from the Emirate of Diriyah, the First Saudi State and the Emirate of Nejd, the Second Saudi State, also House of Saud states.

The Al-Saud had been in exile in the British-protected Emirate of Kuwait since 1893, after their second episode of removal from power and dissolution of their polity, this time by the Al Rashid Emirate of Ha'il. In 1902, Abdulaziz Al Saud recaptured Riyadh, the Al Saud dynasty's former capital. He went on to subdue the rest of Nejd, al-Hasa, Jabal Shammar, Asir, and Hejaz (the location of the Muslim holy cities of Mecca and Medina) between 1913 and 1926. The resultant polity was named the Kingdom of Hejaz and Nejd from 1927 until it was further consolidated with al-Hasa into the Kingdom of Saudi Arabia in 1932.

It has often been claimed that this process caused some 400,000 to 800,000 casualties. However, recent research suggests that though bloody, the number of deaths and injuries was significantly lower.