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.

Originating in the Nejd region of central Arabia, the First Saudi State conquered most of the Arabian Peninsula, culminating in the capture of the Muslim holy city of Mecca in 1802.

The task of destroying the Saudis was given to the powerful viceroy of Egypt, Muhammad Ali Pasha, who sent troops to the Hejaz region and recaptured Mecca.

He then sent many members of the clans of Al Saud and Ibn Abdul Wahhab to Egypt and the Ottoman capital of Constantinople and ordered the systematic destruction of Diriyah.

[18] The Al Saud survived in exile and went on to found the Second Saudi State, which is generally considered to have lasted from Turki ibn Abdallah's capture of Riyadh (which he designated as the new capital) in 1824 until the Battle of Mulayda in 1891.

With the capture of his family's ancestral home, Ibn Saud proved he possessed the qualities necessary to be a sheikh or emir: leadership, courage, and luck.

The warfare period of sporadic battles ended with Saudi takeover of the Al-Qassim Region, after decisive victory in Qasim on 13 April 1906,[27] though other engagements followed into 1907.

[31] In December, the British government (started early 1915) attempted to cultivate favor with Ibn Saud via its secret agent, Captain William Shakespear, and this resulted in the Treaty of Darin.

After Shakespear's death at the Battle of Jarrab, the British began supporting Ibn Saud's rival Sharif Hussein bin Ali, leader of the Hejaz.

An exchange of letters with Henry McMahon assured him that his assistance would be rewarded between Egypt and Persia, with the exception of imperial possessions and interests in Kuwait, Aden, and the Syrian coast.

This however changed after the conquest of Hejaz, when the increasingly critical and negative stance of Ibn Saud on Ikhwan raids developed into an open feud and essentially a bloody conflict since 1927.

In the early 1920s, the repeated Wahhabi incursions of Ikhwan from Najd into southern parts of his territory were the most serious threat to emir Abdullah's position in Transjordan.

[36] The emir was powerless to repel those raids by himself, thus the British maintained a military base, with a small air force, at Marka, close to Amman.

By this time, the few parts of central Arabia that hadn't been overrun by the Saudi-Ikhwan forces had treaties with Britain, and Abdulaziz was sober enough to realize the folly of a potential conflict with the British.

However, a struggle ensued between his forces and those of Muhammad ibn Ali al-Idrisi, who eventually set up the short-lived Idrisid Emirate under Saudi tutelage.

With the disintegration of the Ottoman Empire, a Zaidi state was forged in Yemen under Imam Muhammad bin Yahya Hamid ad-Din and his descendants.

"[43] The Saudis struck back, reaching the Yemeni port of Al Hudaydah before signing a "treaty of Muslim friendship and Arab brotherhood" in Ta'if, which was published simultaneously in Mecca, Sanaa, Damascus, and Cairo to highlight its pan-Arabism.

"[45] Relations indeed remained close until civil war erupted in Yemen in the 1960s, at which time the country became a staging ground for battle between conservative values and those of the Egyptian revolutionary Gamal Abdel Nasser.