Hussein bin Ali, King of Hejaz in the context of "Sharif of Mecca"

A caliphate (Arabic: خلافة, romanized: khilāfa [xiˈlaːfa]) is an institution or public office under the leadership of an Islamic steward with the title of caliph (/ˈkælɪf, ˈkeɪ-/; خليفة khalīfa [xaˈliːfa], pronunciation), a person considered a political–religious successor to the Islamic prophet Muhammad and a leader of the entire Muslim world (ummah). Historically, the caliphates were polities based on Islam which developed into multi-ethnic trans-national empires.

During the medieval period, three major caliphates succeeded each other: the Rashidun Caliphate (632–661), the Umayyad Caliphate (661–750), and the Abbasid Caliphate (750–1517). In the fourth major caliphate, the Ottoman Caliphate, the rulers of the Ottoman Empire claimed caliphal authority from 1517 until the Ottoman Caliphate was formally abolished as part of the 1924 secularisation of Turkey. The Sharif of Mecca then claimed the title, but this caliphate fell quickly after its conquest by the Sultanate of Nejd (the predecessor of modern-day Saudi Arabia), leaving the claim in dormancy. Throughout the history of Islam, a few other Muslim states, almost all of which were hereditary monarchies, have claimed to be caliphates.

The Arab Revolt (Arabic: الثورة العربية al-Thawra al-'Arabiyya), also known as the Great Arab Revolt (الثورة العربية الكبرى al-Thawra al-'Arabiyya al-Kubrā), was an armed uprising by the Hashemite-led Arabs of the Hejaz against the Ottoman Empire amidst the Middle Eastern theatre of World War I.

On the basis of the McMahon–Hussein Correspondence, exchanged between Henry McMahon of the United Kingdom and Hussein bin Ali of the Kingdom of Hejaz, the rebellion against the ruling Turks was officially initiated at Mecca on 10 June 1916. The primary goal of the Arab rebels was to establish an independent and unified Arab state stretching from Aleppo to Aden, which the British government had promised to recognize.

Abdullah I (Abdullah bin Hussein; 2 February 1882 – 20 July 1951) was the ruler of Jordan from 11 April 1921 until his assassination in 1951. He was the Emir of Transjordan, a British protectorate, until 25 May 1946, after which he was king of an independent Jordan. As a member of the Hashemite dynasty, the royal family of Jordan since 1921, Abdullah was a 38th-generation direct descendant of Muhammad.

Born in Mecca, Hejaz, Ottoman Empire, Abdullah was the second of four sons of Hussein bin Ali, Sharif of Mecca, and his first wife, Abdiyya bint Abdullah. He was educated in Istanbul and Hejaz. From 1909 to 1914, Abdullah sat in the Ottoman legislature, as deputy for Mecca, but allied with Britain during the First World War. During the war, he played a key role in secret negotiations with the United Kingdom that led to the Arab Revolt against Ottoman rule that was led by his father Sharif Hussein. Abdullah personally led guerrilla raids on garrisons.